Picklist fields with a value assoicatied to them are not passing into Salesforce

We are currently using the gravity forms Salesforce add on plugin to pass web-to-lead information into Salesforce.

We have a contact form that works as expected, including passing picklist values.

However, we have a second form that uses formula to calculate an estimate. The fields that use the formula are (picklist) fields and each contain a value, however any (picklist) field that has a value associated with it does not pass the data into Salesforce.

For the custom field mapping I have tried using the Salesforce api name (e.g. Project_Location__c ) as well as the unique identifier in the url (e.g. 00NA000000BgWVd ). Neither will pass data.

I have also confirmed the PHP version of the website (5.6) so it should be supported. I’ve also made sure the cache is cleared.

I’ve followed the instructions on this page about pasting the code into the functions.php file https://katz.co/plugins/gravity-forms-salesforce/

I’ve replaced this $name_of_sf_field = ‘ExampleMultiSelectPicklist__c’; with the following:

$name_of_sf_field = ‘Accessories__c,Project_Location__c,Height_of_Floor__c,Deck_square_footage__c,House_square_footage__c,Quality_of_Materials__c,Complexity__c’;

Does the Salesforce web-to-lead addon pass picklist values for formula forms or is there something else I’m missing?