Actually it’s your JetPack plugin that has the Titled Gallery plugin enabled. Looks nice when it’s titled that way but my gallery styling is a column and row layout. I’ve never used the Jetpack gallery, but I believe what it does is override any other gallery styling. You will also notice when clicking on a thumbnail that it opens up with Jetpack’s own lightbox.
One of many joys of confusion with WordPress (and plugins such as JetPack). So I am guessing things are ok then, especially finding out that new info of how it functions? ….which is new to me, so thanks for the follow up details.