Hey welcome back!
Yeah, this is definitely something we need some pictures for! 
You see, the thresholds for transitioning can be finnicky, so we need to look for stuff like that. For instance, say your walk speed is 400, and you have it set to play transition from run to walk when above 400 and decreasing. Well, if anything collides with the character and increases it’s velocity to 400.0000001 now it’s going to play either walk to run or run to walk. See what I’m saying?