Can't export H.264 anymore

Greetings! I'm having a very annoying problem that's been driving me crazy. I'm using the latest version of FCPX and Compressor. Everything worked flawlessly until 4 days ago when I realized that I couldn't export an H264 file. I tried:

Exporting directly to Frame.io: Failed
Exporting to Vimeo: Failed
Exporting a Prores master file: Worked!

I tried transcoding my Prores to H.264 in Compressor but all my H264 presets vanished. I tried creating a new H264 preset but it keeps crashing Compressor. Removing and re-installing FCPX didn't fix it. Removing Compressor and re-installing didn't work.

Adobe Media Encoder works with H.264

Any suggestions?

Trash your preferences. Try exporting master file in H.264.

Trashing preferences doesn't fix the problem. I trashed the FCPX and Compressor preferences. Exporting an H264 from FCPX works but that doesn't solve the issue since batch encoding in Compressor and exporting from FCP to Frame.io are part of my daily workflow. I'm wondering if it's not a Compressor issue since all my H264 presets vanished and I can't even create an H264 preset. I've never encountered this problem.

You don't specify software versions or how you removed and reinstalled Compressor, but assuming you are using the latest version, here is Apple's document on how to completely remove Compressor 4.2 or later before reinstalling:
support.apple.com/en-us/HT203476

Digital Rebellion also sells Pro Maintenance Tools which contains a Compressor repair tool, but I have found the Apple instructions followed by a reinstall have worked the two or three times I needed to do it.

If this doesn't help then you should probably post your system specs and software versions.

Compressor has its own built-in Repair utility now. Preferences, Advanced. Use that, works great.

Also, use the free Digital Rebellion "FCS Remover" to uninstall FCPX and Compressor totally. Then reinstall.

I'd also reinstall the latest Pro Video Support update.

I'm running the latest version of Compressor (4.2.2) and FCPX (10.2.3) with El Capitan 10.11.6.

I removed FCPX and Compressor with Digital Rebellion's FCS remover and re-installed. No luck. I ran Compressor Repair with no luck. I re-installed Pro video Formats and Quicktime. Compressor still crashes when I try to create an H264 preset.

Does anyone have any suggestion on what else could cause this problem?

System specs:
Imac, 2.5 GHz i7, 32 GB 1600 MHz DDR3, NVIDIA GeForce GTZ 780M 4096 MB

This issue came completely randomly.

Compressor has its own built-in Repair utility now. Preferences, Advanced. Use that, works great.

did not know that, Thanks!.

Preferences / Advanced / Reset queue / Repair Compressor

I tried the built-in repair but still no dice. I'm wondering if this could be related to something other than Compressor.

This may be related to a corrupt user account in the OS. You can verify this by creating a new user administrator account on the system. Log into the new user and see how Compressor works. If it functions properly under the new user account, then post back. There are procedures for rebuilding an existing user account that has been corrupted.

I created a new user admin account and still have the same problem.

I was so excited about the new update, thinking it might fix the problem. Still the same issues!!!

I updated to Sierra and it seemed to have fixed the problem. I still can't get Frame.io's uploader to work but I can live with that as long as Compressor and FCPX don't crash.

Thanks for all your input!