Look at his original graphic, above. Since his entry of the Iowa State Fairgrounds came from the county level (USA > Iowa > Polk > County Systems), he has the entire system copied into his Favourites List. The sites are listed in the separate sublisting of "Fairgrounds". He did that correctly! So again, I reiterate that the most likely culprit is that the Service Types weren't enabled.
Looking at his screenshot, and looking
only at the Fairgrounds system, the OP appears to have appended both the Department (talkgroups) and the site (Fairgrounds). What shows in his shot is the department and site as they appear in the database. (What's shown does not confirm that all the site frequencies are there, but the Site (from the database) does show.)
Since most of those talkgroups are tagged as Business, (one is Security), service type would be a logical culprit. Only Public Safety Dispatch service types (plus the generic "Custom 1") are enabled by default when the scanner is shipped, and when Sentinel is first installed. Those are Fire Dispatch, Law Dispatch, EMS Dispatch, & Multi Dispatch. For public safety, you should also enable the related Tac & Talk service types (Fire Tac, Law Talk, etc).
The Casino in his screenshot would also likely use a "Business" service type.
It's a bit confusing, yes, especially with sites listed separately in Sentinel, like that, but as I said, he copied the entire system correctly. Now, on his scanner, he should hit the side menu button (the red three-line button), go to Select Service Types, and go down the list, turning every listing that says "Off" to "On", ignoring the triple dashes (they're not available in this instance), then he should be able to hear what's being broadcast.
In the screenshot, some of the names do appear to match the sites as listed in Sentinel, though we can't verify that with the initial screenshot.
For the Des Moines entry (n the screenshot:
There are three listed TGIDs in Sentinel. All are flagged Interop. That's another service type that is not enabled by default.
However, I don't think service types alone are the entire problem.

For the "Polk County" department under the "SARA Network" header, at least some of the listed talkgroups are public safety dispatch service types (Law Dispatch, Fire Dispatch, and EMS Dispatch to be more specific). Those types should have been enabled by default.
#2. I've been at this a long time and I still forget to check download and monitor
I'd agree that this should be verified. In the profile, in Sentinel, is where you specify which Favorites lists should be downloaded to the scanner, and also whether or not that list should be monitored by default.
Export you Favorite List to an .hpe file, then zip that file and upload it here, so someone can take a look at it, and maybe fix it.
I also agree with this. Export the list and let someone take a peak at what might have been overlooked. If you are unsure exactly how to do this, see this
Wiki article.