Hi Terry,
Sorry for the inconvenience it may have caused.
I did a test with team sites created with Teams on my side, but I cannot reproduce the same problem.
Here my detailed steps:
- Access to a SharePoint team site comes with Teams > Site settings > Click on Site content types under Web Designer Galleries > click Create > select Folder Content Types and setup other properties > OK
Note: The type under Parent Content Types must be selected as Folder. If you select Discussion, the content type cannot be displayed normally in the next step.
- Access to a document library on that site > Library settings > Advanced settings, select Yes to Allow management of content types > OK.
- Back to Library settings, click Add from existing site content types.
- Select Custom Content Types, add Folder 1, click OK.
- Back to the document library, click New, the content type displays correctly.
For the problem you encountered, we need to collect some information to further check it:
- You mentioned "content-type is not even showing in the details pane", could you share with us a screenshot of it? We would like to know which detailed pane is.
- Is there a problem in team sites that not created with Teams?
Appreciate your understanding.
Best regards,
Madoc