TArray64 RangeCheck prints the incorrect error messages for values over 32 bit.
Repro Rate: 4/4
Tested this in //UE4/Release-4.27 @ CL#18319896 and the issue did occur there, it is not a regression.
Results: Intended assertion occurs with the incorrect index and size of the array (Array index out of bounds: -2 from an array of size -2)
Expected: Intended assertion occurs with the correct values of the index and size of the array (Array index out of bounds: 4294967294 from an array of size 4294967294)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-150458 in the post.