Brilliant! That was the missing piece.
Here is the commit that I made to upgrade iOS to GLES 3.0 on a clean develop branch.
I don’t know if all my changes were necessary, or if there are some important ones that I missed, but I now have MRT working. Thank you so much!
It would certainly need to be cleaned up a bit if anyone wanted to support automatically falling back to 2.0, but I’m not sure if that’s a common case given that people usually use 3.0 for its exclusive features.