In the iOS client if you open a task that was already on the waiting list or has just been added to the waiting list and tap the “Show More” under “Contact/Waiting For” section it does not show more contacts. Nothing happens at all, so you’re limited to the 10 contacts listed which results in not being able to accurately move items to waiting for the proper contact most of the time from iOS.
“Create Contact” works and “Show More”/“Create Tag” under the Tags section all work properly. I’ve confirmed this on multiple iOS/iPadOS devices.
I have the same issue when creating a new Waiting For item on iOS. Clicking “show more” does nothing in the “Contact / Waiting For” section. Thus I can only associate a task with a subset of my contacts.
However the “show more” button works well in the “Tags” section.