Problems with direct offline processing

first foray into using direct offline processing with cubase pro 10. having problems.

for example, comped a guitar part from 3 takes, delete overlaps, select all parts, go to direct offline processing and apply a plugin. very erratic results. pops on crossover points, processing not applied to some parts. if I bounce all the parts to a new file and apply it’s fine. it seems to be when applying to multiple parts in separate audio files. it should be able to do this shouldn’t it?