LookML model join is using fields as numeric when they are both defiled as string

[GenDemo]

Hi All

I am getting the following error in a LookML model on a join - it seems to be trying to join post codes as numeric values, even though both dimensions are defined as sting in the respective views.

Any idea why this would be? and how to I get this fixed?

we are using a snowflake back-end.

I have tried to put a ‘to_char()’ conversion in (as below), but this does not seem to translate into the explore window (which is also wierd).