Failing to Stop During Retract

I have an interesting problem in that at times the extruder when retracting (blue wheel spins CCW) fails to stop. It will spin for maybe 5 sec before changing direction, sometimes I have to cancel the print to get it to stop. I’m using the Prusa slicer 2.5.2. I’ve used Marlin 2 & Marlin (legacy), no difference.
Any helpful ideas would be appreciated.