My experience with Allianz, every year before renewal Allianz write asking if the property is occupied and by whom. If the property remains unoccupied, they want to be advised of the intended use / occupancy of the property.
Every year my relation writes back stating the house remains unoccupied and would like to renew cover while options being considered. Letter also points out the house has monitored alarm and is checked regularly. Cover was recently renewed for a third year on a fire only basis. No idea though if it will be renewed next year.
Another relation in similar circumstances replied to Allianz confirming the house was still unoccupied, said nothing about considering options, monitored alarm etc and was refused any cover after year 1.