How to set a variable in Variable Set B from Variable Set A (g_form.setValue not working)

[Mmodi]

Hi ServiceNow Community,
I have a catalog item with two variable sets:

• Variable Set A (where my script runs)
• Variable Set B (contains the variable I need to update)

I’m using an onChange Catalog Client Script attached to a variable in Variable Set A. I’m trying to set a variable in Variable Set B (variable_b), which is a Select Box (Reference) variable.

Example:

function onChange(control, oldValue, newValue, isLoading) {
  if (isLoading || newValue == '') return;

  g_form.setValue('variable_b', 'test'); // doesn't change anything
}

It runs without errors, but the value for variable_b doesn’t update.

Questions:

1. Does a variable being in a different variable set affect how it’s referenced by g_form.setValue() (or should the name work globally on the item)?
2. For a Select Box (Reference) variable, what value does g_form.setValue() expect—display value (e.g., "test") or the sys_id of the referenced record?
3. If it requires the sys_id, what’s the recommended way to set it from an onChange script (e.g., using g_form.getReference() on another field, GlideAjax lookup, etc.)?
4. Are there timing/loading issues where the variable in Variable Set B isn’t ready yet during the onChange of Variable Set A?

Any working examples would be appreciated.

Notes:

• Script type: Catalog Client Script onChange
• variable_b type: Select Box (Reference)

Thanks!