Editing with mpeg2: Media Encoder fails, Premiere export works fine

Short version:

-Editing project with mpeg2 (.mpg) file

-the mpeg2 file was originally an mp4, rendered it with Media Encoder to convert to to mpeg2 as experiment (mp4 was horrendous to edit with, timeline was extremely laggy)

-worked surprisingly well, editing became a dream

-made only 9-12 simple cuts, queued it in media encoder, makes it through the audio process just fine, but fails IMMEDIATELY after the audio portion is done

-tried exporting with only Premiere, worked just fine

-file format was set to export to mp4 (H.264) for both attempts 


other notes:

-Media Encoder set to Mercury Playback Engine Software Only
-GPU Acceleration is on in Premiere

-cleared cache

-tried exporting in new .proj, same issue
-no third party plug-ins used 

Error message:

- Preset Used: Custom
- Video: 1920x1080 (1.0), 29.97 fps, Progressive, Software Encoding, 00;01;27;02
- Audio: AAC, 320 kbps, 48 kHz, Stereo
- Bitrate: CBR, Target 10.00 Mbps
- Encoding Time: 00:00:02
10/05/2020 04:18:25 AM : Encoding Failed
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Frame substitution recursion attempt aborting after multiple attempts on file: C:\projecttest\New Folder\Main Seq.mpg
Inserting black for frame number 266

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