Hi Jon - thanks for your question and welcome to the Qlik Community.
We will be happy to get you the help you need, have you had a chance to look at this video which covers this topic? Let me know if this helps - if not we will continue to troubleshoot.
Main Video Index: New to Qlik Sense Videos
When applicable please mark the appropriate replies as CORRECT. This will help community members and Qlik Employees know which discussions have already been addressed and have a possible known solution. Please mark threads as HELPFUL if the provided solution is helpful to the problem, but does not necessarily solve the indicated problem. You can mark multiple threads as HELPFUL if you feel additional info is useful to others.
BTW here is a video on synthetic keys:
More in 60 videos in case you are interested: