I've tried putting the keyword between slashes as suggested, but it seems to make no difference, it isn't filtering posts in OR out... Is there some other detail in the configuration that I've missed? I can see (via phpAdmin) that the filter text is being written to the database, and I've run the selfoss/update to freshen things up. Despite this there is no change to the posts being displayed, and yes, I am using filter keywords that match items in the post titles... Any suggestions would be appreciated.

Now I know what to look for if I need examples or documentation.

When adding a new source, specifying only a filter word does not do anything besides outputting an error to the log.

I haven't been able to find an explanation of how it works, but I would assume the filter field has a required syntax for it to work.

Can anyone point me in the right direction? Preferably a direction that doesn't require digging into the code.

You have to use the RegEx-Syntax for PHP.

Example:
If you want to use a filte to include only entrys with the word "comic" in it, you have to put
/comic/
in the filter.

I haven't been able to find an explanation of how it works, but I would assume the filter field has a required syntax for it to work.

Can anyone point me in the right direction? Preferably a direction that doesn't require digging into the code.