Warning: Price Action [action id] references Source Field SBQQ__QuoteLine__c.SBQQ__ListPrice__c, which is undefined. If this is unexpected, ensure that the field is JSQC-Compatible, and include this field in a CustomScript to guarantee calculation.

What? What does this even MEAN??

Go look at the Price Action with the action id in the brackets. Might look something like this.

That Source Field has a null value. Move the Source Field value to the Formula field and check for null. Or go debug why your field is null.