It sounds like a cache error. A lot of those have been fixed recently. What, exact, version number of AE CC 2015 are you using? If it's not 18.104.22.168, you're not on the latest version. If you are on the latest version, try clearing the cache and see if that fixes it.
If not, try precomposing your layer (moving all attributes) instead of deleting it.
Just try to add an adjustment layer on top of it?! Maybe it helps!
The version is the actual one. Tested it on 3 PCs; same error.
Thanks for the hint with the adjustment layer. It worked!
..but still it's a bit annoying to make it this way only. :/