"Actually, client has four Fidelity accounts; three of them are personal,"

Personal, of which Type: investment, money market, retirement (of which types)?

"one of them is under the corporation"

That's Never Retirement, unless you are describing Trust funds.

"It turns out that Fidelity did not report any of the distributions for the corp account, which were 12K + 16K"

If that simply is an Investment account, they would not report Removal of funds. They would report earnings and activities, such as on 1099-Int and 1099-Div and 1099-B. Taking or not, isn't part of the reporting.