Can no longer import .DN files into Dimension?

I've used Dimension since it was in Beta. I've used it in my corporate job at least a few times each week since around 2020. 

Sometimes I want to grab something I built in another Dimension file, so I just import that file. Usually I make sure there's not a ton of random elements or hidden things, but it never caused a problem before the latest update. No I cannot import even the simplest DN file into the current one. 

I'm attaching the log from the failure.

This is a pain in the rear because it means if I want to combine elements, I have to re-import them all. If they are exported Illustrator extrusions, it also means I have to re-arrange them all. This is time consuming and a real problem when it comes to consistency.