samba - Nov 2018 - Extensive debugging available for Samba and client on Mac OS?

I'm having some issues with Macintosh users being unexpectedly prompted to
access files on Samba they created and own. I've not been able to determine
a pattern for this. I don't know if this is a Macintosh problem or a Samba
problem, or both. So I'd like to be able to enable more extensive debugging
on the Samba server and if possible on the Macintosh, so I can see if there
are any error messages or warnings as to why users are being prompted for
login when they are authorized to access the Samba share.

I don't see anything in the logs for Samba on the server that shows
attempted user logins or problems. Is this possible to enable? Might there
be a log for Samba client to view on the Macintosh itself? I'm not looking
for a flood of debugging data, but enough to get an answer as to why
Macintosh users are having this problem.

I have considered adding "force" in the Samba configuration file, but
I'm
not sure what would work and I don't want to mask something which might be
a more serious problem such as a bug that needed to be reported. At the
very least I hope to learn more about this situation.

Thanks!

David