Blistering when balling

[Saldawop]

Something that has only happened with my last batch. Once dough has bulk fermented and I divide into balls, as I am shaping them, I am getting blisters appearing on the top of the balls. I tap them down and carry on, more appear.
I presume that isn't normal? Hasn't happened previously, though that isn't much of a sample size for me to go on.
Is it a sign of something I have done wrong? I haven't, as far as I recall, done anything differently.

[The Dough Doctor]

Pictures? It sounds like the dough might have quite a bit of fermentation on it at the time of scaling and balling, a picture would help.
Tom Lehmann/The Dough Doctor

[Saldawop]

Sorry, no pics. When folding into a ball, I use two hands, fold the sides over, turn 90 degrees, fold the sides over and repeat. The top of the ball, I get like a blister, big air pocket, very thin. Sometimes it would be the whole of the top of the ball, tap it down, and fold again, another big blister.
And the dough rose a lot!
In the fridge, after 24 hours CT I had to knock I it back, it had more than doubled, then at the end of the CT(36 hours.),it had more than double again.
Took it out to rest 3 hours before cooking, and it just kept on growing.

Tasted OK, but difficult to open.

[Saldawop]

I did make a smaller batch up yesterday, 2hr RT followed by 6hr CT. Exactly the same issues, although opened up very nicely

[The Dough Doctor]

Your ADY is a bit on the high side for what you are wanting to do, I'd suggest dropping it back to 0.3%. Additionally, you don't say what the finished dough temperature is but from what you are describing it sounds like it is possibly too high (hot), try adjusting the water temperature to give you a finished dough temperature of 70F/21.1C.
Tom Lehmann/The Dough Doctor