I've tried replicating this but have been unable to. I have a button that loops through a grid on screen and added an Insert Into Table action. The attached screenshot shows this insert action. I have run the screen and edited the Insert action several times without losing the value highlighted in the screenshot.
I'm assuming you have a more elaborate setup than I do, so perhaps that's playing a role. Can you give me more information about what's on your particular button, so that I can more closely replicate it?