I have a bunch of replays downloaded and copied over some older ones (still Source 2) from older installs. I can also watch all without issues. The problem is that they have no information besides the date in the Watch Tab. No heroes, duration, etc. That makes it really hard to see what replay is what. This also applies to every newly saved replay or ticketed games.
I have already tried to verify game files to no effect. I also have no second PC to test if it is a hardware or account bound issue.