Getting warning message ''Type of attribute not supported "

Hi,

I have a PA created out of Scrum Template( we have customized it as per our requirement).

There are 2 child PA's point to same Master PA.

When moving a ADT Activity work item from Child_1 PA to Child_2 PA, there are warning message - ''Type of attribute not supported <attribute_name>"

This <attribute_name> is of String List type.

I click on Save button, the ADT Activity work item gets saved but the data in this <attribute_name> gets deleted. Though it is still captured in the History tab.

Does any know the cause/reason behind these warning message and also why the data gets deleted from <attribute_name>?