Compile to eBook hangs

Scrivener Scrivener for macOS
1

PDF and DOCX work fine, but compile to MOBI or ePub2 doesn’t start.

Here I’m about to click Export.

one.jpg
one.jpg2754×2248 627 KB

I get a progress bar at bottom left, but no progress.

two.jpg
two.jpg2758×1844 488 KB

Recent changes were
a) I switched to using Front Matter selected according to Compile Group
b) in eBook Front Matter, I used $include to point to a subset of the Print Front Matter documents.

Scrivener seems to use some CPU time, and there may be glacial progress (not sure), but at this rate it will take hours to complete an eBook compile.

2

The problem goes away when I duplicate documents rather than using $include.

3

Could you please zip up and attach (or send to Mac.support AT literatureandlatte.com) a project that shows the issue?

Thanks and all the best,
Keith