If you are working on a form in LiveCycle Designer which has not just form variables but also object collections and/or script objects all those will be listed on the Hierarchy tab under Variables.
Issue: If you delete a form variable from the Form Properties dialog (File > Form Properties > Variables) the wrong one will get deleted if the variables are not sorted.
Background: On the Hierarchy tab you see all three types of variables: form variables, object collections, and script objects. On the Form Properties dialog you only see the form variables. Designer seems to internally number the variables top to bottom. This will cause a form variable on the Hierarchy tab to have a different internal number than the same form variable on the Form Properties dialog if the three kinds of variables are not sorted.
Example: In the screenshot below the variable “v8_form_variable” is the eighth item in the list.
If you open the Form Properties dialog to look at the form variables the same variable is now the third item in the list, see screenshot below.
If you now delete that variable, close the Form Properties dialog, and look at the Hierarchy tab, you’ll notice that instead of “v8_form_variable” the item “v3_script_object” got deleted. You deleted the third item in the list on the Form Properties dialog but Designer deleted the third item in the list on the Hierarchy tab.
Solution: You can either sort your variables on the Hierarchy tab in the way that form variables appear at the top of the list, see screenshot below. Or you can simply not delete form variables form the Form Properties dialog but directly from the Hierarchy tab instead (right click > Delete).
Reproducible with the following LiveCycle Designer versions: ES2, ADEP, ES3, ES4