As noted in one comment on https://pico-8.fandom.com/wiki/Printh and as I myself experienced during my project, printh seems not to support hyphen/minus character - in file names.

Since the only known special filename is "@clip", I don't see why.

It bothers me in my project as my game title is hyphenated and I use it for the logs. Fortunately, the logs are placed in a local folder containing the .p8, so I can name it whatever I want and it won't be mixed up with logs from my other projects.

Workaround: underscore _ and even space work, so use them instead.

Is there a rationale for preventing usage of this character? If not, could it be allowed in a future version of PICO-8?

I understand that some characters like colon : are forbidden due to system limitations, but hyphen - is supported on all systems I know of.

On the other side, slash / is a risky one but surprisingly, printh does not error directly when you use it. Instead, it will try to write the file, then fail with "printh: could not write file" as the system prevents the operation. Even Windows doesn't accept forward slashes, so I'm not sure why printh would wait for a low-level error on this one.