Steps to Reproduce:

• Add a new statement (eg. diameter, P2386)
• Add a value with a unit of measurement (eg. 12.7 mm)
• Add a value for the qualifier (eg. applies to part, P518) and add an item
• Now try to save all at once

First I thought that the provided reference was the problem, but I got the same result without a reference as well

Actual Results:
I get an error message that the data can not be saved. When I remove the unit of measurement it works. Readding the unit of measurement works as I would expect it right from the start.

Expected Results:
Since it is not a problem after all I would expect it to be saved in one go right from the start

I have a screenshot here: https://postimg.cc/0KrwMvdP
Usecase: .460 Steyr ( Q76000550 )