Hi, did you resolve your issue? I had the same problem until I checked the imported animation’s Platform Target Frame Rate is over 1000! So my guess is Unreal converts your animation to 1000fps, that’s why it took forever.
So I reimported and checked the settings and found out that the Use Default Sample Rate is unticked and the Custom Sample Rate is 0. So in my case, I just ticked the Use Default Sample Rate and it solved my problem. I hope it helps.
