In
Minimal, I don't think there's any way to do that now. You're not doing anything different - the skin has changed.
But
Minimal was never really intended to a be a skin for making albums. It was thought of just as a launching spot for new skin development, with only a few fragments of settings options. These days, it's no longer useful for that - skin development is largely beyond what most hobbyists can tackle, because the expectations for modern page layout are so much more extensive. IMO,
Minimal should be retired entirely.
If you want a simple skin that does, in fact, keep the captions off the images, try
Atom.
https://jefftucker.jalbum.net/skins/atom/