hello @Kass73 & welcome to ABB Community Centre from up in the north of New Zealand.
If you use related keywords in the searchbox you should be able to see how it impacts on insurance in general terms with letting a private room in a home that is either rented or owned.
Am I correct you are living in the property when your Guests/ visitors stay?
Why does your owner think it's different in any way to home/ flat sharing when you have a guest/ visitor/partner stay?
It's no different to having say a Billet in your home.
Insurance companies need a wake up call if they are treating your owners differently because you are using a modern day advertising platform, use the comparison of looking for a job online instead of in the major daily newspaper!
It's time owners spoke up and held Insurance companies to account for discrimination and failing to keep up with the times of technology.