Syndicated from - https://d365demystified.com/2020/03/27/refresh-button-missing-on-roll-up-fields-in-d365-uci-quick-tip/

As we are transitioning to the Unified Interface, some visual cues are a little misplaced or say, hidden.

If your Roll-up field on the Classic UI appeared like this where you could simply click on refresh and update the Roll-up field

classicRefresh

It doesn’t seem to be the case in terms of UCI-
missinginUCI

It’s Hidden!

So, simply click on the Calculator icon –
clickToReveal
And the Recalculate button will be revealed which updates the value
recalculate
And results into the below in my case –
updated
Note: Toggling the calculator icon will reveal/hide the button.

Hope this quick tip helps!!