I had same problem on young dog I have now. My issue started on land blind first leaving line yelping an then she did same thing on water. Only on water it got worse as in vocal the whole time she was swim. I attribute it to pressure on back with burn till going from line an on both land and water blind training. An she did it with over and back cast on sit. She got to were she made sound with no pressure with collar so I knew I had to fix the issue. I think it got worse on water cause she's a barn burner an the water slowing her down. Now first thing first I taught quiet command when she was a pup an would bark in crate which I open crate an gripped her snout an command quiet. I teach all my dogs that. An on command they stop. They might make a muffle growl but they are quiet on command. Now what I did to fix the issue ( did this first on land to get her to understand the correction an then did on water later) was put dog on long lead an as soon as she made sound leaving the line I stopped her with lead walk out to her (which wasn't but a few steps) with NO commands at this point an gripped her snout an commanded quiet and took her to truck an put her in box with an gripped on snout with quiet command again. An repeated it time an time again. Did same thing with her sitting frontal to fix over casts and back casts. Didn't take long on overs and backs cause she knew from back casts from line. Then went to water an did same thing with only change was on over casts and back casts I stopped her short from bank so I could pull her to me with lead if water was deep. As I was pulling her in if I had to was I commanded quiet an she knew at that point her snout was going to get pinch down on. I did take her to truck an put her in box with grip snout an quiet command as I did on land on water training. After many training sessions of that she stopped yelping or barking on any cast I gave her. Oh I left out when I started this training. I put a shackle bird at the blind an let her have it on first back from line so that her drive to get bird would amp her up. So when she went to dog box an not get the reward of live bird as we do on all other training I think was the icing on the cake. Did same on other cast training. I know this was a long reply an I'm sorry for that but it was only way I could explain it. Hope this will help.