I have the same issue , with UK 200 EGLL. GSX L2 works fine at aother airports ive loaded at etc.
Yes, the problem is caused by this file:
C:\Users\ryanl\AppData\Roaming\Virtuali/GSX\egll-qgxgaf.ini
It seems it contains some parking spots with either the jetway or the bridge name blank. If you post that one, I can check it.
My issue also started happening after the new FSDT UI update.
No, that .INI would have caused the same problem in any version, unless you edited it recently during the BRIEF period after the update but before later fix, in which there was an error while customizing jetways, which caused the name in the .INI to be null. The error is fixed now, but it won't auto-repair .INI files changed during that period.