I remember LR losing track of stuff in external drives, that's from deep in my memory and was for an older version of LR.
At that point I actually started using iView Media Pro, which was then sold to Microsoft and renamed Expression Media, now seems seems to have ended up at PhaseOne
Digital Asset Management - DAM - software
The iView product had solved the external drive issue and when using their editor the external drives didn't even need to be attached to edit, albiet this was a low-res edit of the raw settings.
The other thing that was really important to me about the iView product was that it would render raw "as shot". Camera settings actually mean something there, with LR, not so much.
iView's editor was nowhere near as strong as Adobe's but the "DAM" was a lot better.
Not suggesting one over the other, just reminiscing I guess.
What I would suggest though is NAPP.
Learn Adobe Photoshop, Lightroom and Digital Photography | NAPP
I was a member for 4 years and they really can answer your question.
A subscription is worth every penny of that $100.