Capture Age is closing for every single replay I try to watch between 20 and 30 minute in game time. It closes with no message or warning.
When CA closes it switches to the in-game replay which continues to run uninterrupted. I can continue to watch the replay as normal until the end of the replay.
This is relatively recent, in June CA was working without a problem. It doesnt seem to be a hardware problem, monitoring the RAM usage shows its not even at 50%.