object of type 'NoneType' has no len()

[titanvan]

I recently tried to set up my Kustomer Stitch integration to Redshift but I continue to get the following error: "object of type 'NoneType' has no len()". I'm pretty sure I have the right API Keys and starting date -- but what is strange here is that when I kick off a manual backfill -- a bunch of data still populates in Redshift -- whereas when I try to schedule a 30-min job to pull new fields -- I get this error. Help would be much appreciated!