So, weird issue. Hadn't seen it until recently.
When I'm fishing, and the trainer is turned on (and not even using the F8 'make fishing easier' button), I cast the line, and then it just hangs in the air. Can't reel it back in or anything. Can only switch to another weapon. I even started with the trainer (but didn't hit F1 at the menu), fished fine, hit F1 (then the unlimited ammo cheat), and the problem came back. Like I said, it's weird because I didn't have this issue until recently.
N/M on this. Turns out, having 'no reload' turn on affects casting with fishing rods. Turning it off stops this behavior.