As long as this issue has been going on I'm beginning to think it's intentional. Would make sense if it was meant as a fishing nerf. Not a bad way to combat gilsellers abusing fishing without implementing fishing fatigue. Make them catch everything, items and all, not just the high gil fish.

It's not so bad as long as you know about it. Just make sure you reel in anything that's not a monster.

Still happening to me in 2020 btw, if someone knows how to combat this let me know.