I created an additional version for our plan data. I maintained it in SPRO > Controlling > General Controlling > Organization > Maintain Versions:
Version 0 - original plan
Version 1 - 1st revision
Version 2 - 2nd revision
Version 3 - 3rd revision
Version 4 - 4th revision
I tried to delete version 3 and this message appeared:
Message: Bacground job is still running - data can be displayed only!
This message appeared for almost 5 days now and I cannot edit/change the version because of this.