Decision Table returning null (result_elements missing) when called from Flow Designer field script

[adityagalan]

Hi Everyone,

I’m working on auto‑routing RITM/sc_task assignment groups based on the requester’s country.
To manage this logic, I created a Decision Table with two inputs:

• u_user → Reference (sys_user)
• u_catalog_item → Reference (sc_cat_item)

And one result column:

• u_assignment_group → Reference (sys_user_group)

In Flow Designer, inside Update Record → Assignment group (script field), I call sn_dt.DecisionTableAPI().getDecision(). But the flow fails with:

Error: Cannot read property "result_elements" from null,Detail: Cannot read property "result_elements" from null

It seems getDecision() is returning null.

Has anyone faced this issue when calling the Decision Table directly from a Flow Designer field script?
Do reference inputs require strictly sys_id strings in Flow Designer scripts, or is this a limitation of DecisionTableAPI when used inside FD?

Note: I'm aware of Flow Logic: Make a decision, but my requirement is to use script in FD field(Assignment Group field).

Any guidance or working examples would be really helpful.