This may be a duplicate post (Lost formatting after saving), but it doesn't seem like it was properly answered...

I have the most recent version of Wordpress (v 5.2.2) and just created a page (using Blocks, which I don't care much for and need to switch to classic), saved it. Came back to do some style revisions, updated. Everthing looks fine. When I go back to do another revision, all formatting is gone. I've never experienced this before and maybe this is a common occurrence, but I was unable to find anything reporting so besides the post above.

If the solution is as simple as create a new page, ok. But that seems a bit glitchy to me and I was hoping to find a permanent solution.

Edit: I see in the HTML "class="has-large-font-size", so obviously it's there and will probably reflect after updating, but why would it not appear while editing?