.ost file rebuild stops halfway through

I'm rebuilding an .OST file for a user. But it stops at precisely 3,746,376.

The OST is much bigger than that.

OFFICE 365

I deleted the ost file. and restarted Outlook. It builds... but then, once it hits 3,746,376 IT STOPS!

I logged the user onto a brand new Laptop. Opened outlook, and it does the same thing!! O

n a brand new computer.

The OST won't go past that number (3,746,376). At that precise spot, it jams!

The OAW is the same!!

Txs

Thank you