Daisy-chaining Dell MST and non-MST display

Hi,

I wanted to connect two screens to my MBP:

1 DELL U2713H (daisy chainable)

1 DELL U2713HM

so I connected the U2713H to my MBP via miniDP and daisychained the U2713HM via DP on the U2713H. I activated DP 1.2 on the U2713H. The whole system started flickering on Win 7 and then crashed Windows so bad that I had to reboot a couple of times before everything worked with only the U2713H connected.

I also tried it on MacOS and here both screens showed a halfway ok picture, but the same one, i.e. MacOS did not recognize the U2713HM only the U2713H

If I understand the specs correctly, everything should work properly. Any idea why it does not work?