I'm not aware of a workaround other than your suggestion to flip-flop the setting. I guess you could open the community in a private or unlogged-in browser.
But generally the experience around hiding read posts is pretty janky right now. It also hides your own posts in your profile view which is more than a bit silly since you have always read your own posts and wouldn't be viewing your own profile unless you wanted to see one of them again.