Help Provides some information about its owning patch
Author vvvv group
The ID in ParentPatch is suspected to loose data on quitting the parentpatch which is somehow logical.
so on closing it seems to output NIL perhaps in the last frame, which caused strange phenomenons like next patch starting being empty.
no problem anymore after using this workaround
using S+H (Animation) to capture ID once its there:
anonymous user login