"Laura's Bedroom" 202 can't use Hook?

[OysterMug]

I have an old addon room called "Laura's Bedroom" (Room 202.) Works fine in VX. (Annoyingly, despite the name, they didn't include a pose target on the bed itself. Plenty of others. Not the bed. Whatever.) ?

 

For some reason I can't explain, I can't add a H5 LevDef.

 

If I put a "_level_definition.txt" file in the same folder, the room turns black (which typically means you're trying to load an H4 LevDef under H5. But I'm not.)

 

I tried known good LevDefs from other rooms. Still black. Disabling lines/groups inside the LevDef didn't help. Finally, I tried a totally blank LevDef. STILL BLACK! I'm not stuck in a wall. Delete the empty file, and the room appears! ?

 

I've never seen anything like this. Any ideas? ?