eSIM International Roaming on Apple Watch not working

I bought an Apple Watch Ultra 2 recently. I have activated with my carrier which supports eSIM roaming on Apple Watch, but the problem is when I am abroad, after I turn on the cellular on Apple Watch it only tries to search for the carrier from my home country, not the carrier local partner's network (the roaming on my phone works perfectly, it searches for the local network automatically). I have contacted my carrier provider, they said the eSIM with roaming was well-activated and it should work. But it's weird that even though I restart my phone and watch many times it still doesn't work. Does anyone know what may be the cause and know how to fix it?