@JVincentBW,
First question: Are you on the EU server? If so, they have admitted that they are having issues with the app from within Revit working in the EU for whatever reasons. Currently they recommend that you go directly within Chrome or Edge to contentcatalog.autodesk.eu to access Content Catalog. I have a bookmark in my Bookmarks Bar in Chrome which I use. Works every time. I don't even touch the app in Revit. Again, this is only a stop gap, they are working on a fix for the extension so hopefully that will be out soon.
I'm assuming you have version 1.1.2.3 of the app installed? If not, I'd recommend uninstalling your current version and installing that version.
Also you stated that you have cleared your cache several times, but did not state that you have logged out and back into CC at all. Performing that task is actually more worthwhile and pertinent than clearing the cache. Although I do recommend doing that sometimes as well after logging out.
If none of this works for you, I would recommend issuing a Support Ticket through manage.autodesk.com. Content Catalog is now listed as one of the supported applications. If you end up needing to do that, I would suggest providing your ACC account ID found under Account Admin/Settings in ACC.
Also, FYI, Dale was the Autodesk Technician that helped out Jeff. He was never part of this post, so he never saw your message. I just happened upon this myself, so I hope I am able to help you out.
Let us know your outcome! Thanks!
Ric Weber
If this post helps you, please like it or mark it as your solution. Thank you.
My Ideas: https://forums.autodesk.com/t5/forums/recentpostspage/post-type/thread/interaction-style/idea/user-id/12292525