They are still 'looking into it'. Given that this has been going on for over a year with no updates from TCL, you may want to try a work around for the issue. The best workaround that I have found is to buy a Hisense U8G.
Best workaround at the moment is to use a phone that doesnt crash with the TV. There are no specific factors like screen size, OS, model nothing specific to look for you can only test a phone and check if it works. I confirm that the LG G6 works for me and o was able to do the setup. Since its a one time thing my case is resolved, but id like to buy Roku still in the future so id like to get an app update fix for all phones if possible.
Report any phone that works here it will help others. They are usually older phones, but not always. Its so hard to pinpoint.