I created a project through Hub in 2017.3.1f1 while downloading 2018.1.0f2. After the download completed, I updated the project to 2018.1. I also uninstalled 2017.3 and removed it from my Installs list in Hub (being installed before I installed Hub, I'd added it to the list manually), and set 2018.1 as my preferred version. Now whenever I open the updated project, Hub still displays a dialog notifying me that 2017.3 is no longer installed, and offering to either open the project in my preferred install (2018.1) or cancel opening the project. I can proceed to open the project in 2018.1 without a problem. I have not tried playing with it further to see if it's actually a problem when you need to open a project that was updated to any version other than preferred. I also haven't made any effort to get rid of the dialog. It's a minor inconvenience that right now only seems to affect a single toy project, but it seems interesting enough to report.