dash is going in the opposite direction of the cursor.

I was doing a cortex when the dash stopped going forward and started going in the opposite direction, it is like that in any instance.

This behavior is described on the Dash gem itself:

"

If using the "Attack in Place" option, the direction is reversed.

I believe that works with holding Shift while using the skill, or enabling "Always Attack in Place" for the skill.

I don't recall seeing it in PoE, but I do know sometimes modifier keys like Shift can get stuck, even without something like Sticky Keys enabled. If you didn't enable "Always Attack in Place" for Dash, I'd recommend pulling up an on-screen keyboard to see if it's showing Shift as being constantly pressed.