Some proxies failing to export randomly

Hello there!  I've been having this issue for a while.  I do weekly analysis videos of movies, and to better help my workflow, I cut up the entire movie into chunks, export those subsequences, and then import them into a new project that I will edit my video into (it's never the same project as the one I cut up the whole movie in).

I make the project, set ingest setting to "Create Proxies", Adobe Media Encoder opens when I import the files, and up to half of them would just fail for seemingly no reason.

The error message included in these is:

"An error was encountered while writing the output file.  The output destination could not be found.  Check that the output directory still exists.  If the output directory is on a network or external device, check that the connection is active."

My output destination is the same for the files that work and those that don't, and is entirely internal.  The size of the file doesn't seem to have any barring on whether it suceeds or fails, I've uninstalled and reinstalled already (though for an entirely separate issue) but the problem was present both before and after doing so.

All files were exported using the same preset, cut using the same method, and ingested using the same settings and imported from the same folder.  None have repeating titles (I read that people were having issues with that).  They're all .mp4 files if that matters.

The original export settings for the cut up chunks of movie were:

Basic Video Settings: Match Source + Render at Maximum Depth

Encoding Settings: Hardware Encoding + Profile: High + Level: 4.2

Bitrate Settings: Bitrate Encoding: VBR, 1 pass + Target Bitrate (Mbps): 40

No Advanced Settings or VR Video settings.

Use Maximum Recnder Quality, no other bottom boxes checked.

Time Interpolation: Frame Sampling

Apologies if almost none of this information is relevant, just wanted to make sure there were absolutely no questions.

Any help would be much appreciated, as this has been a constant thorn in my side for a while.

I posted this over on the Premiere Pro community, but given it's probably at least half Media Encoder's fault, I figure I might as well post it here too