also Just confirming that from my end, 5.1.1 doesnt do rec light source textures for me at all.
similarly, I work in automotive field, and this one break actually makes Unreal 5.1 completly unusable for any of our design work.
(you basically use rec lights with textures exclusivly when studio lighting cars) .
this one is a major ball drop on Epics acount.
further more, to make it worse,
it was working in 5.1 ( did a whole project in it)
then Unreal auto updated to 5.1.1 and it stopped working,
no easy way to role back to 5.1