Ah, now I get it!
In the serial monitor, you should select "no line ending": with this setting, it should also work with my firmware version. I forgot to mention that you had to use this setting before...
Alternatively, your workaround is also ok but I have tried to keep the firmware as adherent to the original QHY firmware as possible.
At the moment it is not possible to set a different position offset (i.e. backlash value in terms of the firmware) for each filter: it could be programmed, but at least with my wheel a single value is ok for all the filters. If you still have problems centering the filters, try with unidirectional rotation. The main point is not to have the filters perfectly centered on the sensor, but to have the positioning reproducible, so that e.g. flats and lights are acquired with consistent settings.
Best,
Nico