It looks like the Microsoft FLOW might be having an issue wherein in SharePoint when it tries to update a destination list (say "List D") item from a source list (say "List S") item which has a column which contains more than one value (e.g. the list item has an "assigned to" column which can have more than one value for a single item).
Please see my FLOW diagram below. This workflow basically run when an item is "added or modified" on List S, and it adds/updates the entry on List D. (The 'add' vs 'update' decision is made by comparing the "created" and "modified" timestamps). The "addition" part works perfectly i.e. if I add an action item in list S and assign that to two users (user A and B), then the "Add" operation adds two items in List D (one for user A and other for user B). When I "update" the source list then in the FLOW I identify the destination item by comparing the source list item's "ID" stored in destination item at the time of "Add"). During this update operations although the FLOW does update the two items on the list D, but for both the items it updates the user as "B" even though the source has A and B both. The expectation was that it will take the source lists both the IDs and update the destination list one by one for each user ID.
Appreciate any insights.
Please note, since FLOW does not handle "users and groups" columns, I basically pass the "email address" of the user from FLOW into the destination list's email column and then I run a separate native workflow to take the email value and populate the "user and group" column in the destination list. The email and user group stuff works perfectly fine.