I have not tried it myelf yet, but this issue seems to be connected to a general question I have regarding OpenHAB’s handling of configuration files. So I hope it’s okay to jump in here and maybe the whole thing can be cleared up.
I think it may be related to the way or order in which (item) files are ‘processed’. I am not sure how OpenHAB handles item files when starting up and reading/loading them:
Option 1: Openhab reads item file A (alphabetical order?) and ‘processes’ it. If groups are not yet defined (maybe in item file B) then it will be a problem.
Option 2: All item files are first read and loaded without interpreting them. After that they are ‘processed’. This way all items and types are known.
I hope I’m not completely barking up the wrong tree here