The fabric is not on grain, it's that simple. I have always realigned the fabric, never use it the way it comes off the bolt.
Unfold the fabric,, press out the center, hold the 2 selvages edges together, move the fabric left or right untill there is no distortion in the folded edge. There will be bumbs & bubbles in the fold when it is not straight, but as soon as the grain is aligned, the fabric will lay smooth.
I then lay it on the ironning board, press from selvage edge to fold, being sure to keep selvages together. If you get a bubble when pressing, it's still not onn grain.
Have done this method for over 40years & it works, just a little practice to learn.
Good luck