For the benefit of other user the problem and possible solution is described below:

Problem:

User had a file with text choice variable which was set to a particular value, and then the variable was then removed (i.e made hidden from the sidebar).

At a later time the value the variable was set to was deleted.

When the user switched between Tabs, a dialog was shown stating the variable could not be restored.

This is because when switching between Tabs, Omniscope tries to restore all the variables state with the value they are set to.

In this case the value it was trying to restore doesn't exist, as it has been deleted. Omniscope doesn't clean-up the variable old value in case the value re-appears, it simply shows a warning and sets the Variable to a default value.

Possible solution:

The solution to the problem is very simply, re-show the variable and make sure it is set to correct value, by default Omniscope will choose the default value. Once set, you can hide the variable again. This should mean that you don't get the dialog warning you about variable state could not be restored.

Note: You only need to this solution if the variable was hidden (i.e. not being shown in sidebar).