Seems like an odd issue. Just tried the same game and it has the same issue for me. If I cut it down to 78 moves it works, so there seems to be a limit but what the limit is or whether it is a deliberate limit is not clear.
depth 18 Run Report cannot withstand 400-move dummy game
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Jun 29, 2020
0
#3
Apparently Fabian-BOT made 23 blunders with 6.7% accuracy and that was just the first 78 moves 
Jun 30, 2020
0
#4
Indeed 
Before this I did a 200-move game, and despite taking a while it did not have any issues with analysing the game.
https://www.chess.com/analysis/game/live/5074752594?tab=report
Here is a dummy game I played with the 600-rated Fabian-Bot. Obviously you can tell i was merely trying to get as many moves as possible in the game as the last 325 moves are me moving my king around, occasionally pushing a pawn or moving the rook to make sure there was no 50 move rule or repetition; obviously the number of pawn moves i could make were limited and so eventually I succumbed to the 50-move rule (i.e. if 50 white-black moves are made without a pawn move or capture then it's a draw). However, when I tried to run a report, it just refused. The bar at the left of the screen hovered around "ANALYSING 1%" for half a second and then went back to being the computer evaluation. The same happens if I try to turn "Self Analysis" off. Can the depth 18 analysis not withstand this 400-move game? I would like to know why. Thank you!
Note: I'm not sure what category this should be in, I decided on Help and Support.