Hello,
Finally we found how to solve the problem:
https://kb.i-doit.com/display/en/Location+Cannot+Be+Saved
We run this fix before and after import to prevent fail situations.
In i-doit 1.12.2 we introduced a new licensing logic - unfortunately we forgot two places where to strip the code for our OPEN release. This will be fixed with the upcoming Version 1.12.3 in about three weeks.