Mikrotik CCR with Cisco Nexus connectivity issues

Hello,

I’m trying to connect a CCR1009 with a Nexus 3064 via SFP, and have set up one VLAN on the interface.
The issue I’m facing constantly is that while the ports appear to be up in both devices, it takes 30-32 seconds (and obviously, 30-32 pings) for traffic to flow through the VLAN.
I’ve tried it both with the SFP and SFP+ port, using DACs, 10G SFP+ and 1GB SFP, tried forcing speeds etc too, the results are always the same.
I might be missing something on the Cisco side, I don’t know.

Important note is that the Cisco is communicating fine with my ZyXEL switch in my lab, even via vPC. Same with servers, no problem.
Same with the Mikrotik if I plug it in directly to the ZyXEL.

My configuration is:

CISCO:
interface Ethernet1/45
  switchport mode trunk
  switchport trunk allowed vlan 100
  no shutdown
  
MT:
set [ find default-name=sfp-sfpplus1 ] advertise=10M-full,100M-full,1000M-full auto-negotiation=no \
    name=sfp-sfpplus1-nex1 speed=1Gbps
/interface vlan
   add interface=sfp-sfpplus1-nex1 name=vlan100 vlan-id=100

I’m running the latest stable ROS on the MT.
Has anyone had a similar issue?

Sounds like old-style spanning tree. 30-40 seconds for an interface to go from learning to forwarding is about right, and it would block traffic while learning.