Why are most of Subversion's features disabled?

I’m attempting to use the built in Revision Control with Subversion in Unreal Engine 5. I’ve successfully connected to the GitHub repository, but when I right click on a file, most of the options are grayed out. I only have access to Checkout, History, Diff Against Depot, and Refresh.

History works, but if I attempt to checkout a file, I can’t, and I get this error:

svn: warning: W160042: Path ‘AntiqueShop.umap’ doesn’t exist in HEAD revision (405 Method Not Allowed)
svn: E200009: One or more locks could not be obtained

My first thought was the Trunk directory GitHub inserts might be confusing UE5/Subversion, but if that were the case, History shouldn’t work either.