Hello. Just did the Factory reset on my Roku. (had to re-pair remote and re-access Wi-fi)
I added back Plex, but it appears since Roku recognized my account, it auto-added back all my channels I previously had.
This appears to work. (left side now highlighted and available after exiting Plex and re-entering.)
One added benefit- When entering Plex, it now automatically displays all my “pinned” channels without me having to select my Plex server from the menu.
I’ll reverify this all works correctly over the next day, but thanks for the suggestion.