Mandatory UIType 10 field in v7 can't be edited/saved in Detail/Summary View...
I've been "chasing my tail" on this thinking it was my own code that was causing an issue but when I went to demo.vtiger.com I can reproduce the problem.
- Create 2 Organisations and 1 Contact
- Link the Contact to one of the two Organisations
- Make the Organisation field in the Contacts module mandatory
- In the Contact's Detail or Summary View , if you try and edit the Organisation field, you can't save it - even if you select the "other" Organisation