I'm having this same issue. I have some sub channels that have recently changed affiliations and I thought I could just easily change the guide data on these individual stations, but they always immediately revert back to what they were before. Am I misunderstanding this feature or is something wrong here? Thanks for any help.
EDIT: Here's a little additional info that might help. I'm on one of the recent betas, 2025.05.13.2007.
As an example, one of my locals, 6.2, used to be Dabl, but has now changed to American Crimes. The guide provider still thinks 6.2 is Dabl so all the guide data for this channel is wrong. So I go to sources then to my tuner and choose Manage > Manage Lineup. I scroll down to 6.2 and click the pencil icon. After clicking the gear icon and changing the dropdown to Search All Lineups, I find a listing for American Crimes and choose it. Looking at my list back on the Manage Lineup page I can see the correct logo now next to 6.2.
Now, if I close the Manage Lineup page and end up back on the sources list, then immediately click Manage Lineup again, 6.2 no longer shows the American Crimes logo. It has the X instead of a pencil to show I changed it, but the logo area is blank. Redownloading the guide data immediately reverts it back to Dabl.
I later discovered that there is another nearby channel I don't get that also has American Crimes sub channel. So I repeated the above but instead of clicking the gear icon and changing the dropdown to Search All Lineups, I left it as Search Current Lineup and selected that channel's American Crimes sub channel. Interestingly, if I close the Manage Lineup page and end up back on the sources list, then immediately click Manage Lineup again, 6.2 still shows the American Crimes logo this time. But redownloading the guide data again immediately reverts it back to Dabl.