The code below gives an AV on IsOpen := False in Android. After replacings it with ClosePopUp it's working fine.
procedure TTMSFNCTaskDialogForm.BtnClickHandler(Sender: TObject);
begin
ModalResult := (Sender as TTMSFNCCustomTaskDialogButton).Tag;
if Assigned(FTaskDialog) then
begin
if Assigned(FTaskDialog.OnDialogButtonClick) then
FTaskDialog.OnDialogButtonClick(FTaskDialog, (Sender as TTMSFNCCustomTaskDialogButton).Tag);
DoResult(ModalResult);
end;
{$IFDEF FMXMOBILE}
ClosePopUp;
// IsOpen := False;
{$ENDIF}
end;