AGC odd behaviour

I have recently noticed that listening on strong CW signals (i.e S9+ ) I do hear very odd overshoots at the end of the character. Some time ago I had issues at the beginning of the character and was adviced to go from AUTO to a lower latency setting in filters. This, one notch from the lowest latency, seems to improve the AGC issue at the beginning, but having FAST enabled I do get this overshoot at the end. Changing from FAST to MED will remedie this as shown in the plots,  but I would like to continue use FAST without the horrible overshoot. Any suggestions? Latency settings seems unrelated to this.
Flex 6500 and 1.10.16 s/w