Degenerate UVs
May or maynot be a bug.
I have a .ac file that reports 5 or so degenerate UV surfaces, but as far as I can see the surfaces are not degenerate. They do however have 3 vertices in a straight line.
FWIW, there were (now deleted) a bunch of surfaces in this file that I would have called degenerate but which were not picked up by "select degenerate surfaces".
.ac file attached
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