Evidence: the narrowed control did not hold, so a refusal here cannot be told from the server rejecting a three-FieldRef <GroupBy>. What was observed anyway: collapsed HTTP 500 returned 0 row(s) against a RowLimit of 100, labels {"LVChoice":[],"LVNumber":[],"LVDate":[]}, grouping markers [], dimensions honoured 0 of 3 on the collapsed rows ([]) and 0 of 3 on the expanded rows ([]), first row null; expanded HTTP 500 returned 0 row(s); the same query with no <GroupBy> returned HTTP 200 with 100 row(s); ViewXml <View><Query><GroupBy Collapse="TRUE"><FieldRef Name="LVChoice"/><FieldRef Name="LVNumber"/><FieldRef Name="LVDate"/></GroupBy></Query><ViewFields><FieldRef Name="FileLeafRef"/><FieldRef Name="LVChoice"/><FieldRef Name="LVNumber"/><FieldRef Name="LVDate"/></ViewFields><RowLimit>100</RowLimit></View>; collapsed body {"odata.error":{"code":"-2147467259, Microsoft.SharePoint.SPException","message":{"lang":"en-US","value":"Cannot complete this action.\n\nPlease try again."}}}