Visual Studio fails to attach debugger to Unity with no error message

I'm not sure what changed, but I can no longer connect to Unity with Visual Studio to debug.

I uninstalled VS and Unity completely and reinstalled them and I still have the same behavior.

At this point I'm not sure what else to do to get more information on why I can't debug. When I click Attach to Unity, it tries, then returns the button to active without actually attaching. When I click through the menu and select my Unity process on the Attach Unity Debugger, it seems to do nothing.

How can I figure out what is going wrong?