Over the last weekend, I was unable to get data coverage when travelling from US to Canada (Vancouver Metro). I see others comment on this general Canada data issue when roaming, but no movement. In the Toronto area, I’ve had success when T-mobile allows me to use Bell Canada mobile, but Vancouver - no such luck.
I suspect it doesn’t help that TELUS is involved as an smaller provider - I had temporary luck with manually selecting TELUS 3G, but my settings didn’t seem to persist.
I have the Canada/Mexico add on plan for US subscribers and voice calls work fine.