> There is no PAGER or PERLDOC_PAGER environment variable on either computer,

neither PERLDOC ?

> Any suggestions?

perldoc has an elaborated fallback strategy, if one of the backends fails/doesn't fit. For instance it'll just emit plain text° in cmd.exe on Windows, like in your second example.

I can't reproduce your systems, but I would read the docs for perldoc carefully and play around with the options. Especially -oman should explicitly do what you want (see perldoc#-o-output-formatname).

Or the desired backend for the format is not in the path or ... (fill in more speculations)...???

Like this you'll hopefully be able to narrow down the problem.

If that's a plain shipped system Perl without changing any environment, you might need to file a bug report with Mint.

update

you could play around with pager settings

> One useful value for PERLDOC_PAGER is less -+C -E.

and ˛ activate debugging to see how perldoc internally acts

> Having PERLDOCDEBUG set to a positive integer will make perldoc emit even more descriptive output than the -D switch does; the higher the number, the more it emits.

footnotes

°) including wiki-like asterisks * surrounding *bold* text

˛) LAST BUT NOT LEAST! -D will list found pagers and the used backend