I seem to have found a workaround…
I did a cold and dark start on a Cessna 172 G1000 and loaded the TAWS test through. I also spawned a TBM930 at the end of a runway ready to go.
The TBM930 glass cockpit now works correctly from a cold and dark start. I’m not sure which of those 2 was the fix, but either way the script has loaded through and (touch wood!) seems stable now.