Interface starts flapping when added as Stacking Port

[florian_willeke]

Hey everybody!

i am currently very lost setting up a switch stack of 2 ICX7850-32Qs. 

We are using 2 of them and are connecting them via  100GBASE-LR PAM4 10km (QSFP28) and a single mode fiber connecting 2 datacenters. 

Now to the issue. When i connect those 2 switches without stacking enabled everything looks good and working fine. In the moment i activate stacking (of course the stacking port is the one flapping) on one of the nodes the interface start flapping up and down in a weird behaviour. I thought this might be causing because of an old Firmware but even after upgrading and trying multiple firmware versions the issue still persist.

Dynamic Log Buffer (4000 lines):
Aug 12 23:26:45:I:System: Interface ethernet 1/3/5, line protocol down
Aug 12 23:26:45:I:System: Interface ethernet 1/3/5, state down
Aug 12 23:26:44:I:System: Interface ethernet 1/3/5, state up
Aug 12 23:26:21:I:System: Interface ethernet 1/3/5, line protocol down
Aug 12 23:26:21:I:System: Interface ethernet 1/3/5, state down
Aug 12 23:26:20:I:System: Interface ethernet 1/3/5, state up
Aug 12 23:26:09:I:System: Interface ethernet 1/3/5, line protocol down
Aug 12 23:26:09:I:System: Interface ethernet 1/3/5, state down
Aug 12 23:25:42:I:System: Interface ethernet 1/3/5, state up
Aug 12 23:25:32:I:System: Interface ethernet 1/3/5, line protocol down
Aug 12 23:25:32:I:System: Interface ethernet 1/3/5, state down
Aug 12 23:25:31:I:System: Interface ethernet 1/3/5, state up

Has anyone ever dealt with such an issue?

Thanks in advance.