I have an odd issue whereby we have 1 of 2 operators using CUAC 10.5.2.2804 and on 1 of the consoles, when 1 particular contact is looked up in the directory it is showing an invalid number. The other operator doesn't experience this issue.
The CUAC is setup to sync from CUCM and this is working all OK. On the CUAC + CUCM servers I can see the contact with the correct number. The issue is only with this 1 operator.
I will try your 1st point, but oddly enough I have another case of this reported for the exact same issue, but it impacts all operator consoles!
I will also check the client console is connected to the db.