I can't add useful information to this discussion except to note that issuing

sudo sh -c 'echo 256 > /sys/module/usbcore/parameters/usbfs_memory_mb'
fixes my connection problems with running the source code Build: 2021-03-19T15:18:51Z  for both my
ZWO ASI224MC guide camera and
Nikon Z7    (8256 x 5504) => 90.9 Mb fits files
the default usbfs_memory_mb on my ubuntu 20.0.4 was 16  (as noted elsewhere)
The stable version works for me (as one might expect).
Thanks

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