Having troubles opening sprite in "Sprite Editor"

I have recently been assigned to animate a character for a game and after importing everything in, I tried opening the the image in the sprite editor to slice the sprite sheet and i get these errors:

RenderTexture.Create failed: requested size is too large. UnityEditor.DockArea:OnGUI()

and

Trying to read pixel out of bounds.

Now I know I did a little bit of these in the last game I was working on and had no issues. The only thing I could think of was that something has happened with the newest update which I installed before starting my new project. I've tried looking around the forums but am having trouble finding anyone else with the same issue with the newest build. Any help would be greatly appreciated as I am on crunch time for this project.