Welcome to the wonderful world of Beta testing.
Probably related to what’s mentioned in the release notes of SU4b 1.6.5.0:
This build contains a known issue that can cause infinite loading times on certain flights. A fix is in development for a future build. Areas that can cause this issue include, but may not be limited to, the following:
Cardiff
Cliffs of Moher
Darwin
Dublin
Melbourne
With emphasis on “may not be limited to”.
For me it happens anywhere I first load in, then on the next flight I increase TLOD, and try to load in, it gets stuck, and never loads in.
I know it’s not TLOD alone - because I can increase TLOD and load in to any other airport - just not the one I was at previously. Very odd, but suggests something to do with cache, maybe.