i don't know if this is the same or a similar problem.....

i am generating clipart for another program. i make a base character and use a script to generate a new scene file and render for  a set of poses added to the base character scene. it has been working well until recently.

i experienced this with v42 with juni hair and i believe aiko3 with xinxin hair. some prop hair seems to get parented by itself, but i manually parented the hair to the head to be sure. i used poses from different sources. when i looked at the renders, the hair was missing in some cases and not others.

examining the scene files, i found the parenting to be correct but when i looked at the parameter dials, i found the hair had  offsets. when i zeroed them, the hair returned to position. ???  i am adding a zeroing function to my script to adjust but something seems to be different about some poses.

i hope this information is related to the mystery you are experiencing....