Seems like you are missing a ")" after Contains(...).The following should work :)
orders = await _context.Order.Where(x => ids2.Contains(x.ORDERMAPID)).ToListAsync();
Seems like you are missing a ")" after Contains(...).The following should work :)
orders = await _context.Order.Where(x => ids2.Contains(x.ORDERMAPID)).ToListAsync();