Hi, so I've read up on a few posts regarding the problem with not being able to add photos (option greyed out) when importing from an external drive. I've essentially been facing the same problem for the past few months now, and although an occasional computer restart will allow me to add photos, it hasn't been a consistent solution, and I'm wondering how best to address this problem. I'm using a WD Elements 2 TB Drive, and below I've attached info on my lightroom vers. and computer.
Your second screenshot indicates that you are using LrC 9.0. The current version is 10.1.1. I don't know if that would make a difference, but I'm curious as to why you are running such an obsolete version. You need to update. It's possible that your version of the Creative Cloud Application Manager is out of date.