Dear Tahir,

It seems to me that recipe is not balanced, may be bread improver quantity is high and also oil trap inside the dough. You need review your recipe as well as molding and proofing system.

I think the hollow cavity is due to improper make up skills .From the first picture the knot for the final make up of the dough is where the cavity was formed  probably it wasn’t tight enough to sustain the proofing period  ,probably could have caused the uneven leavening of the dough since there could be change in the gluten structure alignment and uneven distribution of carbon dioxide due to irregular air cells
I think the uneven leavening came during baking not during proofing, this could show that the  specific area was more saturated with gases than any other place in the dough that always expand very fast than the rest of the air cells during baking  that is my thought

I think the machine has a malfunction try a control experiment

Try moulding your dough with the hand and bake it then study the results .

There is always in most cases a uniform distribution of ingredients before even the clean up stage And  dough development and since this is a chorelywood technique the ingredients are always distributed uniformly as the mixer keeps running. I won’t look into the recipe so much  and proofing  could have effect on dough volume(height)though it will be uniform like if it’s small all of it will be small .
I think @junaidkhan is right the problem could be moulding

@tahirkhan Your formula is over oxidized and too strong. This is evidenced by the white heels of your bun products. Because your dough is so strong, it is dry, and probably incorporating a small bubble at the rounder bars. You have a panning issue too, where your belts are faster than your pans, hitting on the front of the bun, pushing the bubble forward. I say reduce the gluten (Its really high at 3%)to 1%, or cut your oxidizing system (not sure where it is in your formula). What type of flour are you using, and is there ascorbic acid or ADA in your flour?

The problem has been around for a long time.
And there is no simple solution, because otherwise it would have already existed.
It is common. I see it regularly.
I solved it in my bakery by applying a decoration with an apple divider to the buns.
only the white and brown buns suffered from blistering.
The decoration causes the bladder to burst.

Dear Mohammad

I hoop that the pictures get uploaded.