SlotSet is not functioning in Rasa 3.6

Rasa Open Source
1

Recently, I’ve migrated Rasa version from 3.1.1 to 3.6.20. But with utter surprise, I’ve noticed that SlotSet is not working in my custom action, which was functioning in Rasa 3.1.1.

In the domain.yml, I defined this slot like this below:

my_slot:
  type: any
  mappings:
    - type: custom

And saved the slot value in custom action along with other slots like:

class ActionUpdateSlotValue(Action):
    def name(self) -> Text:
        return "action_update_slot_value"

    async def run(
        self, dispatcher: CollectingDispatcher, tracker: Tracker, domain: Dict
    ) -> List[EventType]:
        my_slot = "random_string"
        my_slot_2 = "random_string"
        return [
            SlotSet("my_slot", my_slot),
            SlotSet("my_slot_2", my_slot_2),
         ]

I can’t guess which part has gone wrong. I’ll be really great-full if you can provide some insights. Thank you in advance.