Path Following Error (Advice, Please?)

Hello everyone.
Ive been working for awhile on a flight game where the player automatically follows a spline through the stage.

Most of the concepts were taken from an old tutorial I read at : unrealenginetutorials.com
I then just added a “AddActorLocalOffset” node & hooked up some controller inputs into it so I could move the ship around obstacles.

However I have a strange issue where the player is constantly offset to their left (local Y) while the path goes positive on the x axis or negative on the y axis (in world space).

I drew an image to better visualize what I mean. (Sorry if my drawing is bad.)
The blue-line shows my spline exactly as it is in the editor but the red-line shows roughly where the player actually goes when I run the game.

I’m new to a lot of this so I don’t know if it’s an issue with my spline but I have to imagine I did something wrong in the blueprints given the consistent way it works.
I’ve spent a long time looking at it & can’t make sense of why it only happens when I’m facing certain directions.

If anyone has any idea of what might cause this that would be great, please.
Thanks for reading.