REI compat has been pretty busted for a while. There's a lot more problems with it than with EMI or JEI.

The JEI support is inherited from Forge, and the EMI support has been maintained by me since it's what I use personally.
REI has had no maintenance besides ports because no active developers use it.

The plan is to eventually abstract support for all 3 behind an API so the same code doesn't need to be written 3 times. But until then, the REI support will remain how it is. It needs a rewrite, and effort is not going to be put into a rewrite that's already planned to be rewritten again. However, Pull Requests fixing bugs with it will be accepted, if anyone submits them.

I recommend switching to EMI + JEI if possible.