role based picklist fields overwritten to empty when user edits record

In Vtiger you have the special field "Role based picklist", in which you can specify, based on roles, what user can see or use what picklist values.

HOWEVER, if a user edits a record in which one of those picklists has a value that the user does not have access to, then saves the record without having touched said field, then the field will be updated with an empty value.

Does that make any sense? Personally I would expect that, if the user didn't touch the field, it would keep its original value.