When clicking on a Statblock folder in the sidebar, the entire sidebar is completely removed from the page and there is no way to get it back until refreshing the page.
Click on "Statblocks" in the sidebar, then click on a Statblock folder.
im in the same boat (I'm using opera GX)
This should now be resolved. Issue was indirectly due to the FontAwesome outage earlier today, and the patch we attempted to circumvent their outage.