So, I have an existing page on my wiki. I've placed all the content within <translate> tags, and I have a <languages /> tag at the top. But absolutely nothing changes about the page after I make this edit. There is no languages bar anywhere and there is no way to mark the page for translation. There's nothing in MediaWiki's job queue holding it up, and I followed the instructions when installing and configuring the language extension bundle. I am sometimes able to get it to work on certain pages, but on other pages nothing happens at all. How do I get the extension to work consistently?
Topic on Extension talk:Translate
Unfortunately I have no idea since I have not seen such behavior. You could try the tips from Manual:How to debug to see if there are any errors or warnings that could give clues.
Have you tried visiting Special:PageTranslation directly?
Special:PageTranslation did not list the page at all.
After digging through the debug logs, I eventually figured out that it was being caused by an unrelated extension (Cargo) throwing a missing database table exception during the saving of the page, which somehow prevented Translate from doing its thing. After recreating the Cargo tables, I was able to get Translate working again.
Wasn't easy to troubleshoot this as the wiki interface never indicated an exception.