Don't know if this will help, but it's worth a try, at least:
Highlight the ITV (or ITVX whichever is there) item in your channel grid and press the * key on your remote.
Remove the channel
IMPORTANT! DON'T SKIP: Restart your Hisense Roku TV via Roku menu path Settings > System > Power > Restart System. (Note, if you have "Fast Start" enabled on this set, a quick OFF/ON will not give a complete restart - use the menu path or unplug/replug the power cord.)
Reinstall the ITVX app from the Channels store.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X