Dryness problem in our burger bun

Dryness problem in our burger bun...we are giving 3 days expiry to customer...but 2nd day dryness problem in our bun.

We use

novamyl pro enzyme 0.03%

Hydrolcolloids gums    0.16%

Water   62%

Bread improver 0.14%

Preservatives calcium propionate 0.11% and potassium sorbate 0.10%

Fresh yeast 4.44%

Sugar 12%

Salt 1.67%

Oil 3.56%

We first make sponge then after 2 hours make final dough...

Proofing time 1 hr ( 35c/ humidity 85%)

Please guide....