IPhone says roaming data is turned off when it isn’t

I am travelling in Europe with an iPhone 12 mini, with an eSIM from home (Australia) and a travel SIM from 3UK. The travel SIM has a 30 day life (for some resta il reason from the company that I bought it from). Last month worked perfectly; I could access Mobile data without a hitch. However when I put this months SIM in Mobile data no longer works. I get messages saying “Data Roaming is turned off” but I don’t even have a switch to do this. The only control I have is to have Mobile Data Off, from the 3UK SIM, or from the Australian eSIM. Any ideas? Thanks