Error on ClientDataSet in Tokio 10.2

After the installation of RAD Studio 10.2 Tokio, and not in the previous version, my code give me an error.

When i assign a valid index string to the property IndexName of a ClientDataSet (not always but often, but i don't understand why) the code give me this error:

Access violation at address 4DB0D009 in module 'midas.dll'. Read of address 00000000.

These are the the steps before the error:

4db0d009 +000 midas.dll
0079489a +062 ... Datasnap.DBClient TCustomClientDataSet.SwitchToIndex
00794a72 +07e ... Datasnap.DBClient TCustomClientDataSet.SetIndex
0079516e +002 ... Datasnap.DBClient TCustomClientDataSet.SetIndexNam

The problem is inside SwitchToIndex procedure i think, on the row:

Status := FDSCursor.UseIndexOrder(MarshaledAString(MetaDataFromUnicode(IndexName)));

What could be the reasons be?