I use three apps on my Roku almost daily. Roku Media Player is for watching media from my home server via DLNA, then YouTube and Prime Video. With all three I often watch media that lasts over 30 minutes without getting kicked back to the home page. While it's rare that I've watched a YouTube live stream that lasts that long, I have watched some SpaceX launches that lasted over an hour. I don't think there's anything within the Roku firmware that is causing a return to the home page after 30 minutes. But what's causing your issues, I can't venture a clue. Hopefully tomorrow when the Roku forum admins are here again they can do some investigation for you.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.