Can’t select all versions of Unity when upgrading a project high on the list in Unity Hub 2.0.0
Thank you for reporting this.
It is a known issue, and we are addressing as we speak and going to ship the fix in the following releases.
As an ugly workaround, you can select 2019.1.3f1 in this image and you should be able to select that.
Sorry for the inconvenience
Cheers 