I have a possible reason that reflects my current cynicism with much of the managed rental pool in town. Your unit may be one the management company considers to be at high risk of foreclosure.
If the property gets repo’d, the tenant’s deposit (if held by the original landlord) is gone and the tenant may ask the management company to cover it. Also, the management fees may end up delinquent and unrecoverable.
I recently saw management company freeze a landlord’s account when the NOD showed up. They announced that they would be escrowing the deposit for return to the renter if the property was taken by the bank. This is not just altruism. Some of these situations end up in court.