I can confirm this still happens in 5.4.4.
I stumbled upon this issue when I was creating a reload animation with a shotgun where I have 3 different animations; Intro, Main Loop, Outro. Where I start by playing Intro then I play Main Loop for however many bullets need to be reloaded and then I play Outro.
I found that this issue is exactly 1 frame, so if you play at 120 fps you can’t really see it that well compared to 30 fps where 1 frame is longer.
Currently the only “fix” is as you said to introduce a blend out time, which works, until you play at 30 fps where you need a longer blendout time which doesn’t work well for our case.
It would be great to see this issue fixed as it currently is the main roadblock for our animation system.