You also wrote: "every time I click Print or View Prior Year Return and never asks me to pay to upgrade. and "brings me back to homepage."
That's the main reason you are unable to pay. You are choosing the wrong option.
After upgrading to PLUS, and when paying at the Print Center, you do NOT choose to view/print prior year. You are paying for the current year to unlock the prior-year return. So to get the payment screens you have to say you want to print this year's 2018 return. Then it will ask you to pay. You do NOT have to actually print the 2018 return, but you do have to say "view/print this year's return" in order to get the payment screens. I know it sounds bizarre, but you are paying for the current return (by trying to print after upgrading) which will unlock the prior returns as a side effect.
Before doing that, however, you should figure out why a 2017 Deluxe return is locked in the first place. You should still have free access to it. We can tell you how to phone Customer Support if necessary.
