It looks like this is caused by the Timer.cs code, which catches IOExceptions but not UnauthorizedAccessExceptions. https://github.com/Unity-Technologies/ml-agents/blob/2352955052b30bbd5c7f13276e847f2ee5af5b8a/com.unity.ml-agents/Runtime/Timer.cs#L480 This happens when the file [gamedata]/ML-Agents/Timers/[GameName]_timers.json is owned by someone else.