X3b - Nudging muted ProChannel!

Issue description:
 
I nudged vocal clip 1 x 10 ms to left in loop mode - normal workflow I've done zillions of times. This time vocal track was suddenly muted. Track output to Vocal bus was OK but bus output was silent.  After disabling whole ProChannel audio came thru. ProChannel modules were (from top to bottom): PC76, PC2A, Tape Emulator, EQ, Console Emulator. I had to restart project to get audio working again.