The membrane plumbing in your photo looks to be correct, so we can rule that out.
What I would suggest is to isolate each membrane so that you an identify if one, or both, membranes are the cause for the issue. In other words, remove the water saver membrane and test the one membrane on it's own. If it functions normally, you know that membrane is good to go. If it doesn't, then that membrane is the problem. Then swap the membranes to test the other.
Alternatively, if you have a hand-held TDS meter, you can simply unhook each product line from the y fitting after the membranes and test each one for TDS. If one is high, then it's likely that's where the issue is coming from.
The likelihood of both brand new membranes being bad would be very very low.
If you do find that one of the membranes is faulty, our customer service team can certainly get a replacement sent out.