Slitherine

If you are working with the Text1.txt file and you open up a mission you would need to close out of the campaign if you make any other changes to the text file.

I also believe you need to close the file as well but did not verify that much ...

But remember that if you keep the campaign open and edit the file you will still get the same text before it was updated. Apparently the file is loaded in RAM while the game is open and unlike the script files the game does not update the copy of the file in RAM once the file is saved while a campaign is in play.

Just exit to the menu where you chose a campaign. Then re-enter the campaign and the updated file will be loaded in RAM.

Same with graphics files, like icons, etc.