Okay, well, it appears that the lights I released with the DLK break under P5. An already-lit light will work and can be moved, but any attempt to use the ERC controls to change the colour or anything will fail. As a result, the solo lights I released with that package that start out 'off' simply aren't able to be turned on. Most people's solution (or, rather, workaround) to this is to open one of the 'L' props and steal the light from that. P4 and PPP have no problem with 'em, and it seems like some something to do with the ERC crosstalk fix in P5 somhow broke the EC for the lights altogether.