IPCB fader with 2 cues?

for Example: I have a cuelist with 2 cues. Cue 1 - Intensity sin; Cue 2 - intensity - step. I configure the fader as IPCB & persist on override. I start Cue 1 (intensity sin) and move the fader to 50% - OK. Intensities sin wave from 0-50% - if I push go (Cue 2 intensity step) the fader shows 50% but the output intensities show 0-100%. The fader gets non functional. I have to move the fader to 100% or to 0. After that the IPCB works on Cue 2. This has been an issue since Hog 3. is there any useful explaination for that behaviour?