Tile palette messing up sprites

I imported individual 2D sprites to use as tiles. I only change the PIxels per Unit from 100 to 64 for all sprites. The rest remained default. The Sprite Editor shows the sprite correctly.

I then create a new Tile Palette and when I add a tile to it, it gets displayed like this:



Whenever I move the mouse the tile vertices move around with and it keeps on warping.

Is this a Unity bug or did I mess up the import?

 

I also had the same problem, it happened to me when I tried adding my own custom made tiles to the tile palette. Before this, when I first started the project, it was fine, I was able to import tiles into the palette without any issues. The only way I've found to fix this is to create a new unity project, and copy all the assets over to the new one.

Edit:
Ok, it seems the culprits were the preview packages 2DAnimation and 2D PSD Importer. I am using Unity 2018.3.14f1, and it only happens when tiles are imported AFTER these preview packages are installed, even if you remove the preview packages, the problem persists. So stay away from these two packages until you've made all the tiles you need.