Parallel exports - output names getting confused

I export edited wedding images for clients in three resolutions, each in its own subfolder and with its own file suffix:

_FULL (full size)

_HD (1920px)

_FB (1024px)

The exports are all run together at the same time.

I've been doing this since switching to C1 in 2019 and never had any issues.  But recently, I've found that sometimes the wrong suffix is being added.

For example; in the FB subfolder, some of the files will have the 'HD' suffix.  The pixel resolution of the file is correct (1024), but the suffix is wrong.  Doesn't seem to be any pattern as to how frequently this happens, but if I export 300 images there's typically about 20 or so with the wrong suffix, but it does vary.

If I run the export individually, it's fine.  The problem on happens when they are being run in parallel.

This never used to happen.  I *think* it started when they released the 'correction' to v14 and reintroduced the Export tab, but I'm not sure.

Anyone else seen this?