Success! Thanks so much for your help. The update did the trick, I finally now have the slider which is going to be so incredibly helpful. One last question... I watched DJI's tutorial on updating using the Assistant, and at the end of it, there was a mention of having to repeat the update for every set of batteries that will be used? Does that make sense to you? It did say that the computer would not need to be connected to the Inspire for additional battery sets... but still, it seems weird.
A funny side note... as frustrating as this was to figure out, it did save my butt in another way. I had been out of town last week with my Inspire, and had not needed to recharge anything since I've been back. In fact, I spent all my flying time just taking the batteries down to safe travel levels. If I had not needed to recharge them to get the screen grabs today, I would not have noticed that I must have left my power cord for the charger on my last shoot! Thankfully, discovering this gave me enough time to get another spare (I have two chargers) picked up in NY by our director who I'll be joining on location in Spain. Silver lining!