punching animation is glitched in the engine, but looks normal in the gif itself

my punching animation is glitched in the engine, but looks normal in the gif itself.
what is this caused by and how to fix this?

ENGINE:
https://imgur.com/a/zpr49AO
GIF:

 

Are you by any chance using Aseprite or Pyxel to create this animation?

 

yes, i am using aseprite.

 

Try using this custom animation importer. Here's a tutorial if you're having trouble. I'm not a pro in any way, I was trying to import my animation into unity for the first time yesterday and also having some weird glithes. If this doesnt work, try exporting in different ways (as a spritesheet, as separete png's etc.).
The importer did solve the glitch that I was having, but it introduced some new ones. Strangely enough, saving the aseprite file in my project directory and exporting as separate png's by pressing shift+alt+ctrl+s for whatever reason solved it, I'd suggest trying the stuff above first though. Hope this helps or anyone who actually knows what's going on comes along.

 

Also, maybe try to update unity to the latest version