Just hopping on this thread to say thanks to gavin310 for their workaround/fix on this issue. It’s a shame the direction ACF has been going since WPE/DB bought it.
This is the solution I ended up using. For whatever reason, my rewrites weren’t working when I was registering the CPT and taxonomy via ACF (order didn’t matter); with registering them as code in functions.php, then it worked.
