Mail Search doesn't work / Flagged folder inactive

Hi

I am having sudden problems with Apple Mail. I have 4 Gmail accounts connected, and had no problems until recently.

Everything seems fine except for 2 critical things:

- Search doesn't work at all
- Flagged folder only shows when highlighting specific flagged messages, yet remains seemingly empty. when reopening Mail, the Flagged folder disappears.

I tried the following, to no avail:

- deleted "Envelope Index" files and rebuilt.
- ran Disk Utility and repaired disk & permissions.
- reset Spotlight search using Login items.
- restarted in Safe Mode.

Maybe this is a sympthom of another problems, I don't know, everything seems to work just fine.

Help would be much appreciated 🙂

Thank You!

____

Using a MacBook Pro (15-inch, Mid 2012), running on Mavericks OS X 10.9.5

Processor: 2.6 GHz Intel Core i7

Memory: 8GB of 1600MHz DDR3 memory
Mail / Version 7.3