UIDocumentBrowserViewController shown repeatedly on Big Sur

I have a Mac catalyst app that has a root view controller of a UIDocumentBrowserViewController. When a document is selected, the editor view controller is presented modally (in fullscreen mode).

This worked fine on iOS 14, and macOS Catalina, but when I run it on Big Sur, the editor VC will appear for a second, and then disappear, and the UIDocumentBrowserViewController gets shown again.

(Not sure if the editor is being dismissed, or if another UIDocumentBrowserViewController is being shown on top.)
Upon more testing, clicking "New Document" will successfully show the template chooser modally, and from there the editor VC can be presented successfully as well. Not sure why this works, but not directly opening the document.
Same issue here: Thread
As I mentioned on the other thread you referenced, I worked around this by not presenting my document's view controller until after my document had completed opening. Apparently on catalyst, the document browser vc actually dismisses itself when we present something on top of it.
UIDocumentBrowserViewController shown repeatedly on Big Sur
 
 
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