Ah, okay, that explains the AddType and AddHandler difference. Thank you. 🙂
I kept coming across people suggesting AddType when I searched for information, but my current .htaccess does use AddHandler to enable SSI for .html, and that works fine. I do, btw, remove that when testing for PHP, as I was told you can't enable both for the same extension.
I'll give AddHandler another try, perhaps I have missed something in my .htaccess that is interfering. Should I, for example, have an AddType text/html .html directive in there as well? I do currently, since I was told that to enable SSI, I needed both AddHandler server-parsed .html and AddType text/html .html, and I thought the same was true for PHP too.
I do know that my host has AllowOverride All and Options All set (and I use .htaccess successfully for other things, like SSI), but what is FileInfo?
Edited to add: I tried AddHandler application/x-httpd-php4 .html and AddHandler application/x-httpd-php .html, but neither did the trick.