My recent experience for anyone still having issues... I'm using Android (Samsung S20) from Canada. I have never been able to get tip board to work at home. Went to WDW in December with a US data package and still did not work. It only loaded if I was on WiFi. It was a hassle since the coverage was spotty, but I was able to get by. I decided not to chew up vacation time troubleshooting.
Fast forward to today, still not loading the tip board from home. Tried support chat and they basically said try us again when your trip is closer. Found this thread and downloaded a VPN app and that did the trick. Now I can play around with it until our next trip in August and I'm hoping it will also solve the issue of it only loading on WiFi while I'm there. Or better yet, Disney will have it fixed.