A lot of stuff here but just work though it slowly... try to answer all the questions you can here before diving into do stuff.
As already asked, what is the buffer size ...and what is your session sample rates? Both are super critical.
It won't record without crashing -- what about just playing back prerecorded audio? Drag and drop some existing MP3, or whatever into some audio tracks.
And while we are here, what *exact* Mac Book Pro model? Model code name e.g. MacBookPro6,1 or better Model number better EMC code. Look for stuff printed on the back of the MBP.
Unfortunately you may have wasted some time here, like worrying about hardware/memory issues or jumping to doing a new macOS install before troubleshooting other things.
Confirm what exact playback engine device you have selected in the playback engine. I want to make sure you are not using an aggregate IO device to aggregate your UAD interface with the MBP built-in output or anything else, since this AAE-6101 relates to CoreAudio problems.
Where are you recording the audio/session to? Hopefully the internal MBP SSD. But check the session content is really going there, not say unintentionally to some slow USB stick etc. Do all the tests below with new empty sessions, not clones, not from templates, recording to the internal SSD.
Did Pro Tools installed just with ILM and no other drivers or plugins ever work on the original OS install? On the new OS install? i.e. using it just with built-in output and no interface drivers or plugins installed?
Has Pro Tools on this MBP ever worked? If so what changed?
Hopefully you are working at a conservative sample rate, if not do that now and work at 44.1 kHz until you get stuff working. You should have tried increasing the buffer size until things work. Did you try that? So it is still not working at 1024 samples?
With UAD plugins instantiated in Pro Tools (not the UAD console) you should expect to need to be running at much larger IO buffer sizes that with similar native plugins. You say you are not using plugins, but I want to make sure you understand the issue with the UAD plugin architecture. And don't have say UAD plugins running on hidden tracks. UAD plugins in Pro Tools are for mixing (with large IO buffer settings) more than tracking (with lower IO buffer settings).
Have you tried everything here
http://avid.force.com/pkb/articles/e...-Pro-Tools-Mac ?
And more basic housekeeping:
Get the mac fully optimized, every last thing on the standard optimization list done. e.g. WiFi disabled bluetooth disabled, etc. If you think it's been done before double check it again..
In the playback engine dialog:
Uncheck ignore errors (you want to see as many errors as possible while troubleshooting)
Set the disk cache to 2GB ("normal" is off).
Unplug all hardware you don't actually need from the MBP. Mice, keyboards, USB hubs, external drives, etc. unplug it all. Just connect the MBP power supply, UAD interface and iLok if you are using one. When testing without the UAD interface unplug that as well.
Make sure other programs, web browsers etc. are not running.
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If you don’t know if other software might have broken Pro Tools when you added it then your job now is to peel everything away until it (hopefully) works.
As always start by trashing prefs and doing that between other main steps below. Use Peter Gates' tool.
http://petegates.com/pg-pt-prefs.html
Move all .aaxplugin files out of the plugin folder. Trash prefs. Start Pro Tools, it will automagically put back the default plugins. If Pro Tools now works OK, move the third party plugins back in batches until you find which ones are bad.
If moving all plugins out did not fix the problem, then don't put them back.
- Uninstall *all* the UAD software. Disconnect the UAD interface.
With built-in output as the playback engine just try playing back content.
With an aggregate of built-in output/input try to see if you can record anything (e.g. using the MBP internal mic).
... still a problem... then maybe do a clean new macOS install. But come back here and tell us the details of what you have done/seen so far (take notes as you do all the above).
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Basic optimization stuff is under troubleshooting links under "help us help you" up the top of each DUC web page.