Why does Set Variable not work?

I set up a series of text variables to be bound to some text boxes in UMG.
They were working all day yesterday and today.
And I have not touched them since getting them setup yesterday.
After finally getting my resolution option buttons working in UMG, those previously working text variables are no longer being set at all.

The image below shows that the variables are not actually being set.

14772-brokenue4umg.jpg

Upon reloading the editor, all the values were cleared.
I suspect that they had been cleared at some point, but the editor had failed to update it.
I still don’t know what caused it.
But I have moved the values into a text struct which I use to set those variables, and have not had problems since.