Render fails in AME but succeeds in Premier

I just finished an edit on a 1-hour show, and this version of AME doesn't like it.

The 1080 24p timeline consists of a base track 4KUHD  MXF covered by occasional 1080 PNG stills and a 1080 MOV reference track  The MFX details, from Sony FX6, are:

Wrapper type: MXF OP1a (type: SingleItem SinglePackage MultiTrack Stream Internal)
File generated by: Sony, Mem (2.00)
H.264/MPEG-4 AVC Long GOP High Profile 4:2:0 Unconstrained Coding
Bitstream Format: Sony
Class 100

We are rendering to a 1080p output using "Match Source - Low Bitrate"

When queued up in AME, rendering quickly stalls. Elapsed time says first 10 minutes then 55 minutes, then 2 hours, then it bails.  Error logs point to failure to read a frame in the MXF.  Also Windows performance monitors show little activity in CPU and GPU.

But if I render directly out of Premier, it works fine, renders in about 10 minutes flat, and CPU/GPU are running at 100%.

So something is going on with AME.

    Application: Adobe Media Encoder (Beta) v23.5.0.16
    OS: Windows v10.0.22621, RAM: 63.87 GB GB, CPUs (logical): 16