routed port connected to a trunk port

We have a 6814 w/ a routed port that is connected to a 3650 with a trunk port, and all works well.

Configs:

6814:

int x/y ip address x.y.z.2 255.255.255.0 

3650:

int x/y switchport mode trunk 

int vlan 1

ip address x.y.z.7 255.255.255.0 

From what I understand, this should work (and does) by default as vlan 1 is untagged. However when we try to put in a 3850 with same config/parameters, the link comes up but no traffic goes across. I'm going to have them try to add native vlan 1 to the port, but vlan 1 should be untagged by default, correct?