1.48 refers to the firmware version. Version 1.55 added a new option for parameter 52 for on/off. You can also try setting parameter 3 (ramp rate) to 0 for instant on.
I’m not totally sure on this, but my suspicion is that the dimmer isn’t rated for the load produced by a ballast, which I think may be inductive. Just because the dimmer is capable of always putting out a full output does not mean the electronics behind it support that type of load.
I don’t disagree if it was trying to ramp up the voltage, but it sounds like it should go to 100% instantly. It works just fine after the 1.5 seconds, so I don’t see an issue once it’s at 100%. Going to look into upgrading the firmware per stu1811 and try the on/off setting.
@DriftN2Forty Just as an FYI, the dimmer does not officially support fluorescent loads and I’d recommend swapping to a switch and using the dimmer elsewhere. I’ve actually killed a few fluorescent fixtures even with proper on/off settings after about 6-9 months of use. Haven’t killed the DIMMER, but I did end up removing it and replacing it with a switch and no further issues after ~1 year.