Consegui resolver o mesmo problema usando OPENQUERY em vez de EXEC:
insert into rowcount_sub (tablename,rowcnt)
SELECT * FROM OPENQUERY(svrA, 'select ''col'', count(1) from test.dbo.[Table1] with (nolock)')
Espero que ajude alguém...
insert into rowcount_sub (tablename,rowcnt)
SELECT * FROM OPENQUERY(svrA, 'select ''col'', count(1) from test.dbo.[Table1] with (nolock)')