I got the same error when trying to watch the replay for match 6960. After watching a different replay and coming back to the main menu I was able to download and watch the match fine on my second try.
First attempt:
Second attempt:
Sorry about the screenshot quality, not sure why it looks washed out. Took them using Steam. Looks fine for me when playing or recording, and I don't have an HDR display.
I was having the same problem. Followed your footsteps. I was able to download and watch another match and then backed out and the previously broken replay was now working.