I have a Pixel 3a, with a 150GB tariff which includes O2 Travel Inclusive Zone. I was able to use 4G in the US back in February with this phone and tariff. I'm back in the US today and I don't have any network whatsoever (I'm at the same place as last time).
I triple-checked that roaming is enabled on my phone, I tried selecting the carrier manually (it doesn't find any), this is the exact same phone, tariff, and place as last time so I really don't know why this happens. I checked in my profile that I have O2 Travel Inclusive Zone, and I even enabled the O2 Travel bolt to see if it would change anything, but it doesn't.
This is quiet frustrating because I signed up to a 24-month contract with the 150GB tariff at the beginning of the year precisely to allow me to use roaming when I travel to the US (I really don't need the 150GB otherwise). Before that I was on a much cheaper tariff, and out of contract. Also not having internet meant I drove "blind" (no GPS) until I resorted to stopping at a nearby Starbucks with a wifi to be able to download offline maps of the area. Not something you want to have to do with jet-lag after a 9h flight.
