Today:
Cannot OLCI on iphone app: it is a flight to Canada, one way, and after entering my US passport details I get an error message. Ten attempts trying different ways to enter my name (middle name, no middle name, space, no space...)... Fail.
Call DL support: it is security, nothing you can do, "in these times", etc... Cannot admit that their technology failed.
So I try on delta.com on a computer... And there appears an additional field asking for the date I will leave Canada (the return flight is on a different ticket and airline). I entered it and got my boarding pass.
Conclusion : there is a limitation in the app and the support was unable to handle it. Instead, they blamed it on "security", tough times etc... And did not care about me losing my spot on the upgrade list. However the solution was simple.