Hello - I am having the same problem. My data roaming does not work in New York. I am from Canada and got the phone from fido in Winnipeg.
Let me save you some time: airplane mode is off, data is one, roaming is on, i have data left on my plan, there are no data blocks on my account. I have verified the access point settings. I already tried turning my phone on and off. I already tried resetting the network settings.
Having no access to data left my high and dry on my trip. Called 3 times and troubleshooting would randomly work on the phoen for an hour then lose connection to mobile data. Brutal experience.
Welcome to the community
I can understand how difficult it can be when you depend on your phone for work and are not getting access to your data.
From what you mentioned, I see that you have done most troubleshooting steps at this point.
However, I do have another question.
Have you tried selecting another network in the U.S manually?
option is to use an prepaid usa sim, via Target or walmart. make sure it has data as well. (place an voicemail tell others to call u on usa #, and on facebook wall, or twitter, mention the new usa # too).