I have a number of blank entries in the Modern UI application folder too as well as one called 001fa. I thought I could right-click, Properties and check the Hide option but I noticed that one of the Mail accounts which I choose to pin to the Start screen disappeared so be careful about doing that. I suspect that the other blank entries are also Start screen apps that Start8 is not detecting correctly. Either way, the blank entries look like a bug so I'd like to see a future update of Start8 either detect these and show them properly or not display them at all.
Incidentally, I have an issue with the tile for Rocket Riot 3D, which I bought from the Store, not displaying on the Start screen and I'm wondering if this was an app I inadvertently hid by mistake (i.e. it was one of those blank lines). I can only play this game through the Game app, where it works perfectly, but I can't uninstall it because the only way to do so is from the Start screen and there is no tile! I suspect that if I could uninstall the reinstall then it would display the tile properly. This issue may not be related to Start8 though; it may just be a coincidence that I came across it at the same time as I noticed the blank lines in the Modern UI applications folder.
*EDIT*
The blank lines are favourites I added to the Modern UI Internet Explorer app that I also chose to pin to the Start screen, e.g. Play.com, HMV, Amazon and YouTube. The 001fa entry is my Karoo mail account pinned to Start screen from Mail. These are obviously not being displayed by Start8 correctly because they are normal tiles but optional ones pinned their by users.
*EDIT 
Sorted out Rocket Riot 3D issue as I noticed it was listed in the Modern UI applications folder but not on the Start screen. When I checked the shortcuts properties it had the Hide flag set. Unchecking that then made it visible on the Start screen. I must have accidentally hid it when I was trying to remove those blank lines.