When doing a minimal org copy from Production to Sandbox in the Dynamics CRM Cloud rollup fields become “invalid” during the copy. These invalid rollup fields show up in the UI on a form with an amber-colored icon with an exclamation point (as pictured above). This bug has been reported to Microsoft and they have confirmed it is happening in their own sandbox organization test.
As of this writing (mid-October 2015) the Product Team is aware of the situation but there is no date yet for a resolution.
Further details that may help you deal with this situation if you are faced with it in your Sandbox org:
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