Hi Al,
In r62794, r62795, and r62796 the IDE interface was refactored. Ideally you should go back to r62793 and stay with that version until things are sorted out.
I don't have Mojave, but I assume svn is still available. Try this:
1. Open a terminal
2. Go to ../fpcupdeluxe/lazarus/ folder
3. svn up -r62793
4. Open fpcupdeluxe, go to setup, check "FPC/Laz rebuild only" or something similar
5. Press only Lazarus
Ps: After everything is done, don't forget to uncheck that checkbox in option