Recent experience, HNL-ORD. I am waitlisted with plus points for first, but not Prem+. I am #2 for first. #3 for first is also #1 for Prem+.
#1 for first gets upgraded. At the same time (#1 Prem+ and #3 first) gets upgraded to Prem+ AND jumps me to be #1 for first, I'm still #2.
How can this happen? Obviously had an economy ticket if got "upgraded" to Prem+.