europe cellular data service not working

I am the original poster who had this issue and wanted to close out this thread with what I eventually learned once I got back home in the USA.  I am hopeful that this helps others from experiencing the frustration I had with my T-Mobile International service.

It appears that my issue was due to an enabled "International call block feature" that nobody told me about even though I had specifically called T-Mobile ahead of my planned International trip.  My phone had International calls blocked and this is what prevented it from registering successfully on any European T-Mobile service network.  This feature was likely enabled years ago while I was a Sprint customer and carried over to my T-Mobile migration.  Why all 5 lines on my plan didn't have this enabled, I have no idea. The solution is to contact T-Mobile using the 1-800 number, wait 30-60 minutes for someone to pick up the call, verify you are the owner of the account, and then request the feature be disabled.  UNFORTUNATELY, when you are out of the country and don't have service calling isn't possible and there is no way to reach T-Mobile via a web chat or email (which work fine when on WiFi).

Hope this helps others and also alerts T-Mobile to the need for other ways to get service when out of country. They also need to check this feature is not enabled if a customer pro-actively calls to ask about International service capabilities and costs.  (They should have caught this when I called to check in advance of my 3-week trip abroad.)