Tags Not Added To New Contact

step 1) New contact details are added to a new spreadsheet row

step 2) That new row triggers LeadConnector V2 to create/update a contact in GoHighLevel

step 3) Lead Connector V2 then adds a tag to the new/updated contact

Seems pretty straightforward, but every time it fires, the contact is created/updated in GHL but the tag is not added.

I get an email stating that the contact is not found (see below - real email address swapped out obviously)

Any idea as to why the contact is not found? 

Thanks in advance,

{
    "error": "Contact with id [email hidden] not found",
    "status": 400
}