I might be wrong but I have the feeling it is similar to my problem here: Change variant of other component
What I guess with my very limited knowledge: as soon as you switch to Active Tab 2 Variant of your tab bar the field on which the set variable action is connected to is no longer on the canvas (because it is on variant 1 of your tab bar). Again, I’m just wildly guessing because I have a very similar issue and no solution so far. Seems like an easy task but Figma doesn’t seem to be capable of or at least does its best to hide an obvious solution.