Custom field of type "multiple objects", CSV import fails with: not a valid value

[uppsju]

I'm running 3.6.2 of Netbox, and I'm having some issues importing virtual machines with custom fields of type "multiple objects".

I first created a cluster called "eu-de-1"
I also created a custom field called "cardinal", of type "Multiple objects", and of object type "Extras > Tag"
The tags are (all lowercase):
east
west
north
south

Looking at the description of tags in Field Options for virtual machine import, it reads:
tags — slug Tag slugs separated by commas, encased with double quotes (e.g. "tag1,tag2,tag3")

My import looks like this:
name,status,cluster,cf_cardinal
test,active,eu-de-1,"west,north"
test2,active,eu-de-1,west

No matter which value I put in the custom value cf_cardinal I get an error during import "is not a valid value". If I create the VM in the GUI and assign the tags, then it works fine.
What am I doing wrong?

Thanks!