Editing xdcam-ex files on M1 macbook pro

sounds like it's an issue with "spanned" clilps.  Spanned clilps are when the camera hits the file size limitation of the drive format you recording to.  If you iimport the containing folder, Premiere will usually bring in the individual files and also create a clip that's the "combo" file which you can find looking for the duration of the imported clips.     Luckily haven't had to do this in a while and it's possible it's been broken in the latest updates. 

You might check out a 3rd party app, EditReady

https://hedge.video/editready

which will transcode the clips to a more robust editing format and combine the clips...    It's a great app and you can set up presets and batch process files...  and even use it to make proxies.

And be aware, if you're going to be sending your final edit to resolve for color correction, spanned clips will be a nightmare... so EditReady definitely has some advantages.  

When I posted this issue a few years ago here, I was told to used MediaBrowser to import the clips in to Premiere rather than the file: import dialog or simply dragging the folder in from the OS.    Gotta say MediaBrowser did not solve the problem for me, but might be a worthwhile test to see if it solves your problem.  

Hi Plankt_ON,

We're sorry about the poor experience. Have you tried running the app in Rosetta mode & then importing the files from Media Browser to check if it's working properly?

Thanks,

Sumeet