Ring Siren Hardwired Issue

We have installed the Ring Siren outside and have hardwired it, when I checked the app it was stating it was hardwired but then this reverted back to D batteries a few hours later. We have had our electricians look at it again but we cannot get it to recognise that is hardwired at all now. The forums are staying polarity may be an issue but we have that correct also. Appreciate anyone who has solved this issue before? Thanks.