There are some Windows 10 users who might have a lot of items in their Start menu. However, if those people have put in more than 512 items in the menu, there's a known issue that will cause it to "eat" those apps or crash a lot
As reported by Petri, the bug happens if a user has over 512 files of any type placed in the Start menu, which includes a folder with that number:
"After doing this, if you click on your Start menu, the results become inconsistent and vary greatly. I have experienced lag time of up to 15 seconds for the menu to open, clicking 'all apps' will occasionally crash the menu and like others, some apps simply go missing from the menu. Other times, the menu would not open at all and clicking the Start button several times resulted in nothing and required a restart to get it to open again."
Users can simply delete the folder in the Start menu with all those items to eliminate this issue. Microsoft's support forums indicate they are aware of the problem and are working on a fix "but apparently changing the size of the data structure caused a number of unforeseen cascading changes."