Just came across this problem, thanks for the work around DAGGADA2, ya little lifesaver :)

I have also been struggling with this problem. The dropdown menu completely loses all interactivity when timescale=0. The workaround script from DAGGADA2SEP worked though.

@DAGGADA2 thanks!

@DAGGADA2 great fix

Happening to me as well. Was not happening prior to 5.2.1p3. Thank you for the temporary fix, previous poster. =)

This served as a workaround for me, just drop this script on the below the Dropdown component on the gameobject:

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
using System.Collections;
using System.Collections.Generic;

// delete this when unity gui fixes timescale issue with dropdown widget
class DropdownPausedFixer : MonoBehaviour
{
void Awake()
{
EventTrigger evtrig = gameObject.AddComponent<EventTrigger>();
EventTrigger.TriggerEvent trigev = new EventTrigger.TriggerEvent();
trigev.AddListener((eventData) => Fix(eventData));
EventTrigger.Entry entry = new EventTrigger.Entry() { callback = trigev, eventID = EventTriggerType.Select };
if (evtrig.triggers == null)
evtrig.triggers = new List<EventTrigger.Entry>();
evtrig.triggers.Add(entry);
}

public void Fix(BaseEventData eventData)
{
// If paused, remove the spawned dropdown
if (Time.timeScale == 0f)
{
Transform tr = transform.Find("Dropdown List");
if (tr)
Destroy(tr.gameObject);
}
}
}

Yes, also experiencing this. It seems their fade-in tween for the content area is not timescale independent. You can see the the spawned "Dropdown List" object's Canvas Group component's alpha remains 0 when timescale is 0. If you manual override it to 1, the list will appear.

Might be able to temporarily work around with a click event trigger and forcing the Dropdown List's canvas group to alpha 1.