Incorrect Default Content Type in Document Set

[nullorempty]

In my Document Set settings, I have the Allowed Content Types set as:
Red, Blue, Green
The Default Content / Content Type is set to Red.

When a user uploads a file to a Document Set, the default content type is being set to Yellow and the Yellow content type is visible in the New Item form.  The Yellow content type was once associated with the Document Set content type and is still part of the library due to documents being associated with it. 

Note:  The library contains a Black content type that was also associated with the Document Set but it does not appear in the New Item form.

Enviroment:  SPO
Library experiance:  Classic

[#2]

@nullorempty Is it similar to the bug i demonstrate in the attached video?

[#3]

We are experiencing this as well. Is there a solution or response from Microsoft? Thank you for the video.

[#4]

In my example. the library in question had a few documents tagged with the Yellow content type. If those documents are removed or migrated to a new content type, the default content type will no longer default to Yellow.

I opened a ticket with Microsoft, spent a few hours on Teams calls explaining the issue over and over, the ticket was escalated, then closed with no resolution or followup. Microsoft support appears to have been 100% outsourced and opening a ticket is cruel waste of time. And we are paying for "premier support".

[#5]

We also opened a ticket, with a result of "by design".

TRANSLATION: We know that the current behavior is not the desired (logical) behavior, but that's just the way that it works and we do not intend to change (fix) it.

[#6]

Good demonstration. I am also annoyed by this - but there seems to be no hope that MS is fixing this.