Cannot change default block font size from dropdown

For the last few weeks (perhaps since wp update?), I cannot change the default font size in the block editor using the dropdown menu.

For example,

If I want to change the font size of a paragraph block, when I attempt to select the font size (eg, “medium”, “large”, etc), the selection snaps back to default.

I can workaround by choosing the “customize” option and enlarge fonts that way; however, the spacing does not adjust accordingly, so the large fonts end up overlapping slightly between lines of text.

Although there’s a link to a specific post page, I’m finding that this issue applies to any page that I create (post, page, etc).

Any suggestions are greatly appreciated!

The page I need help with: [log in to see the link]