Odd. So the workbook itself is dual axis, and multi data source (Oracle). I did some more testing. I can make a NEW workbook and recreate and everything works fine. I can also make a new sheet within the old workbook and the analytical functions work fine. However the existing sheet when opened with the latest version loses all analytical functions and they can not be re-added even I remove everything from the view. So I would have to recreate a very complex view if I want to upgrade, is there another step I can take, or perhaps this is a known issue?
Instead of having to recreate the view, have you tried copying and pasting the worksheet to a new workbook? If you copy that to a new workbook, and the reference line works there, then you should be able to paste it back into your original workbook (where hopefully the reference lines will work) and then replace the copy and pasted datasource with the original.
Thanks for your response Paul. This was an interesting idea, I hadn't tried it. I can copy and paste the worksheet into a new workbook in Tableau 2018.2.2 and the reference lines work fine. If I copy from 2.2 into 3.2 the lines are removed and can not be re-added. Everything else works and shows fine.