V. 14.0.1 appears to drop video levels in .mp4 encoding on a Mac

All,

I recently updated to v. 14.0.1 and when converting a ProRes HQ .mov out of FCPX to an .mp4 using AME I am seeing a 15 IRE drop in level. Not 100% sure if this not a gamma shift - I don't think it is. The encode was done using a user preset that encodes properly in v. 14.0. I also tried using the stock YouTube .mp4 encoder and I'm seeing the same level drop. I also tried both hardware (GPU) and software only rendering. I'm on a 2013 Mac Pro, running OSX 10.14.6.

Any ideas? Maybe a new bug?

Thanks!

Bill