For context, I'm building almost exactly what was described in this post and am running into the same problem. When deleting items from "instances" in a Flex Repeater, I get stale styling from the deleted items on the item below the one that was deleted. I think this is because Ignition uses the array index for the React "key" prop under the hood, and so React doesn't know how to match up the deleted data with the UI.
I think this may also have caused the problem described here.
React docs reference: https://legacy.reactjs.org/docs/lists-and-keys.html#keys
Is it possible to pass in a custom value for the React "key" prop for Flex Repeater child views from Perspective? Or is there another way to get around this issue?