Good day, Eric:
This is the case I submitted: https://customer.nintex.com/cases/Pages/detail.aspx?caseId=5002v00002qKHoCAAW. If you would like, I can show you the issue via MS Teams/Skype if you send me an e-mail with your contact information. I was able to resolve the issue on my own by not using variables and instead I directly coded the functions into rules.
For example, this is one of the rules to populate a field on the form:
lookup("Vehicle Info- Data","ID",convertToNumber(parseLookup([Form].[Lookup Years],false)),"Constant Color") + " +"
Originally I used two variables for this (maybe three).
Referencing a variable in a rule seems to be a known issue in Nintex for SharePoint 365. Attached is a copy of my form. The three fields at the top of the form, Lookup Make, Lookup Model and Lookup Years, all lookup data in another SharePoint list. My rules then populate the rest of the form. It also seems like that if you have a variable and it is not populated on the form, this causes problems as well, which is why I nested the formulas. This is probably more efficient, but since I am not a programmer, it was a bit confusing at first.
I originally created variables to do this and made the variables the default value for these fields. However, when I went to submit the form, it would not submit most of the time. Although, on a few instances it did. This is when I submitted the original help desk ticket and started browsing the forums. I came across an issue where other people were having problems with variables and lookups, and decided to see if I could do away with variables, which is when I went the route of using rules and putting the functions directly in the rules.