Okay, it seems that something went wrong with BEE2 and made the sendificator not export with the map. The original version I put up would work perfectly for anyone with BEE2, but show a giant "ERROR" in place of the sendificator for anyone else. The current version, which I tried to use pakrat to fix for people without BEE2, has a bizarrely shiny sendificator. If anyone has advice on how to fix this problem, let me know; I have no idea what I'm doing and just let pakrat do auto, and manually looking around for the right files didn't help because I don't even know what they are.
Easiest is to install BEE2. I reinstalled it and then found you took down the map...oh well...
Did you rename the map at any point? Sounds like the cubemaps are broken. You may want to run the stylechanger exe again if you haven't, the Portal 2 updates would have reverted the vbsp/vrad modifications preventing the packing from working.
I tried having BEE2 export the settings (which is as far as I know equivalent to using stylechanger again), then exported the map into a bsp by "publishing" to a hidden file from the modified pti, then told pakrat to auto-include files, during which it found a bunch of sendificator-related files (but I think not all of them?), and then went and tested the result using the console's "map [filename]" command, never once changing the filename. I got exactly the same problem as before, and no new ones: It still has a bizarrely shiny sendificator. Is there some file missing that pakrat wouldn't know it needed and/or wouldn't know where to find?
I've experienced that with Sendtors in the PTI before, it's caused by unbuilt cubemaps. Put your BSP file in dlc2, open the console in your map and buildcubemaps. Then publish.
The stylechanger exe does do something different when you open it up, installing the various hooks needed to modify the compile. When I played your map (great puzzle by the way), the cubemaps were definitely messed up.
It looks right now, right? Because it looked good on my final test of it, and I can't know what my computer won't show me.