Can an unoccupied property still be an HMO

HMO Licensing

I applied for a HMO license last year as under the council's additional licensing scheme as it is a house converted to self contained flats before 1991 i.e. it is a S257 HMO. The council has been innundated with applications and is still processing mine and has yet to make a decision or even visit.
Since I submitted my application for a license all my tenants have left as I am hoping to sell the house with vacant possession. I have no intention of renting again and have advised the council of this.
The council have asked me to apply for a temporary exemption notice (TEN) but this only lasts 3 months.It has taken me 8 months to get vacant possession and I have no idea if I will be able to complete a sale in 3 months during this current crisis.
If I understand the regs correctly I believe that as the property is totally unoccupied it is therefore not an HMO. Is this correct?
Thanks