I use Home Assistant with Zwave2MQTT with the LZW31-SN, but not experiencing these issues (even with the ramp rate set to 0.
OZW logs when turning light on and off
$ tail -f OZW_Log.txt | grep Node011
2020-04-23 02:54:15.017 Detail, Node011, Received: 0x01, 0x09, 0x00, 0x04, 0x00, 0x0b, 0x03, 0x20, 0x03, 0x63, 0xba
2020-04-23 02:54:15.018 Info, Node011, Received Basic report from node 11: level=99
2020-04-23 02:54:15.018 Detail, Node011, Queuing (Send) SwitchMultilevelCmd_Get (Node=11): 0x01, 0x09, 0x00, 0x13, 0x0b, 0x02, 0x26, 0x02, 0x25, 0x19, 0xf4
2020-04-23 02:54:15.018 Info, Node011, Sending (Send) message (Callback ID=0x19, Expected Reply=0x04) - SwitchMultilevelCmd_Get (Node=11): 0x01, 0x09, 0x00, 0x13, 0x0b, 0x02, 0x26, 0x02, 0x25, 0x19, 0xf4
2020-04-23 02:54:15.018 Info, Node011, Encrypted Flag is 0
2020-04-23 02:54:15.026 Detail, Node011, Received: 0x01, 0x04, 0x01, 0x13, 0x01, 0xe8
2020-04-23 02:54:15.026 Detail, Node011, ZW_SEND_DATA delivered to Z-Wave stack
2020-04-23 02:54:15.043 Detail, Node011, Received: 0x01, 0x07, 0x00, 0x13, 0x19, 0x00, 0x00, 0x03, 0xf1
2020-04-23 02:54:15.043 Detail, Node011, ZW_SEND_DATA Request with callback ID 0x19 received (expected 0x19)
2020-04-23 02:54:15.043 Info, Node011, Request RTT 25 Average Request RTT 25
2020-04-23 02:54:15.043 Detail, Node011, Expected callbackId was received
2020-04-23 02:54:15.061 Detail, Node011, Received: 0x01, 0x09, 0x00, 0x04, 0x00, 0x0b, 0x03, 0x26, 0x03, 0x63, 0xbc
2020-04-23 02:54:15.061 Info, Node011, Response RTT 43 Average Response RTT 45
2020-04-23 02:54:15.061 Info, Node011, Received SwitchMultiLevel report: level=99
2020-04-23 02:54:15.062 Detail, Node011, Refreshed Value: old value=0, new value=99, type=byte
2020-04-23 02:54:15.062 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:15.062 Detail, Node011, Expected reply and command class was received
2020-04-23 02:54:15.062 Detail, Node011, Message transaction complete
2020-04-23 02:54:15.062 Detail, Node011, Removing current message
2020-04-23 02:54:15.062 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_SWITCH_MULTILEVEL Instance: 1 Index: 0
2020-04-23 02:54:15.126 Detail, Node011, Received: 0x01, 0x0b, 0x00, 0x04, 0x00, 0x0b, 0x05, 0x5b, 0x03, 0x09, 0x80, 0x02, 0x2d
2020-04-23 02:54:15.126 Info, Node011, Received Central Scene set from node 11: scene id=2 with key Attribute 0. Sending event notification.
2020-04-23 02:54:15.126 Detail, Node011, Refreshed Value: old value=0, new value=1, type=list
2020-04-23 02:54:15.126 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:15.126 Info, Node011, Automatically Clearing Scene 2 in 1000ms
2020-04-23 02:54:15.126 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_CENTRAL_SCENE Instance: 1 Index: 2
2020-04-23 02:54:16.127 Detail, Node011, Refreshed Value: old value=1, new value=0, type=list
2020-04-23 02:54:16.128 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:16.128 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_CENTRAL_SCENE Instance: 1 Index: 2
2020-04-23 02:54:18.466 Detail, Node011, Received: 0x01, 0x09, 0x00, 0x04, 0x00, 0x0b, 0x03, 0x20, 0x03, 0x00, 0xd9
2020-04-23 02:54:18.466 Info, Node011, Received Basic report from node 11: level=0
2020-04-23 02:54:18.466 Detail, Node011, Queuing (Send) SwitchMultilevelCmd_Get (Node=11): 0x01, 0x09, 0x00, 0x13, 0x0b, 0x02, 0x26, 0x02, 0x25, 0x1a, 0xf7
2020-04-23 02:54:18.466 Info, Node011, Sending (Send) message (Callback ID=0x1a, Expected Reply=0x04) - SwitchMultilevelCmd_Get (Node=11): 0x01, 0x09, 0x00, 0x13, 0x0b, 0x02, 0x26, 0x02, 0x25, 0x1a, 0xf7
2020-04-23 02:54:18.466 Info, Node011, Encrypted Flag is 0
2020-04-23 02:54:18.474 Detail, Node011, Received: 0x01, 0x04, 0x01, 0x13, 0x01, 0xe8
2020-04-23 02:54:18.474 Detail, Node011, ZW_SEND_DATA delivered to Z-Wave stack
2020-04-23 02:54:18.494 Detail, Node011, Received: 0x01, 0x07, 0x00, 0x13, 0x1a, 0x00, 0x00, 0x03, 0xf2
2020-04-23 02:54:18.494 Detail, Node011, ZW_SEND_DATA Request with callback ID 0x1a received (expected 0x1a)
2020-04-23 02:54:18.495 Info, Node011, Request RTT 28 Average Request RTT 26
2020-04-23 02:54:18.495 Detail, Node011, Expected callbackId was received
2020-04-23 02:54:18.514 Detail, Node011, Received: 0x01, 0x09, 0x00, 0x04, 0x00, 0x0b, 0x03, 0x26, 0x03, 0x00, 0xdf
2020-04-23 02:54:18.514 Info, Node011, Response RTT 48 Average Response RTT 46
2020-04-23 02:54:18.515 Info, Node011, Received SwitchMultiLevel report: level=0
2020-04-23 02:54:18.515 Detail, Node011, Refreshed Value: old value=99, new value=0, type=byte
2020-04-23 02:54:18.515 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:18.515 Detail, Node011, Expected reply and command class was received
2020-04-23 02:54:18.515 Detail, Node011, Message transaction complete
2020-04-23 02:54:18.515 Detail, Node011, Removing current message
2020-04-23 02:54:18.515 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_SWITCH_MULTILEVEL Instance: 1 Index: 0
2020-04-23 02:54:18.581 Detail, Node011, Received: 0x01, 0x0b, 0x00, 0x04, 0x00, 0x0b, 0x05, 0x5b, 0x03, 0x0a, 0x80, 0x01, 0x2d
2020-04-23 02:54:18.581 Info, Node011, Received Central Scene set from node 11: scene id=1 with key Attribute 0. Sending event notification.
2020-04-23 02:54:18.581 Detail, Node011, Refreshed Value: old value=0, new value=1, type=list
2020-04-23 02:54:18.581 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:18.581 Info, Node011, Automatically Clearing Scene 1 in 1000ms
2020-04-23 02:54:18.581 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_CENTRAL_SCENE Instance: 1 Index: 1
2020-04-23 02:54:19.582 Detail, Node011, Refreshed Value: old value=1, new value=0, type=list
2020-04-23 02:54:19.582 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:19.582 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_CENTRAL_SCENE Instance: 1 Index: 1
2020-04-23 02:54:21.358 Detail, Node011, Received: 0x01, 0x10, 0x00, 0x04, 0x00, 0x0b, 0x0a, 0x32, 0x02, 0x21, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xcf
2020-04-23 02:54:21.358 Info, Node011, Received Meter Report for Electric - W (1) with Units W (2) on Index 2: 0.0
2020-04-23 02:54:21.358 Detail, Node011, Refreshed Value: old value=0.0, new value=0.0, type=decimal
2020-04-23 02:54:21.359 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:21.359 Detail, Node011, Refreshed Value: old value=false, new value=false, type=bool
2020-04-23 02:54:21.359 Detail, Node011, Changes to this value are not verified
2020-04-23 02:54:21.359 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_METER Instance: 1 Index: 2
2020-04-23 02:54:21.359 Detail, Node011, Notification: ValueChanged CC: COMMAND_CLASS_METER Instance: 1 Index: 256
Do you have the HASS Discovery option turned on in zwave2mqtt, or are you manually configuring things in Home Assistant for this switch? It could be that zwave2mqtt is just reporting things incorrectly to Home Assistant.