Cookies–brilliant! So, I run all my browsers in Strict Privacy mode with NO 3rd Party Cookies. I was able to fix it by doing this:
In Chrome I went to Settings > Privacy > Third-Party Cookies > Sites Allowed to use Third Party cookies and added an exception for [*.]huggingface.co.
So, apparently, when you Duplicate Space directly in Private, it tries to create a third party cookie to enable the “App” window. But all Public spaces do not use third-party cookies? And if you go Public → to Private space, the 3rd party cookie is also not required?? (Edit - I was always logged into my account, of course, and I continue to be logged in.)
Makes me think there is something funny about Security when you go from Public → Private… But maybe that’s my tin foil hat getting too tight?
Anyway, good call, @John6666. I’ll have more security-related Q’s in the future, but this gets me off and running!