After upgrading to mqTranslate 2.6.4, all my <!--more--> ("Continue reading →") and <!--nextpage--> (for multi-page posts) were ignored. The Home-page just displayed all posts in their entirety and the pages of multi-page posts all showed the post in its entirety.
Simply put, it was like the tags were not there.
Downgrading back to 2.6.3 solved the problem. Looking at the diff between 2.6.3 and 2.6.4, I see some changes involving these tags, so the problem must be somewhere in there, but I don't know where.