It’s no secret that Windows 10 just like any other new version of operating system has been riddled with issues, some of them come with a workaround and some need you to fix it manually. The problem of Office apps missing from All app list is one such issue. While it is very difficult to zero in on a single cause for this problem, it might have happened if you have more than 512 apps in All apps list.
It is a known issue in Windows 10 that if you go for more than 512 apps, their shortcuts will disappear from the Start menu All apps list. Microsoft has information on this and they are apparently working to remove the cap.
Office apps missing from All apps
If shortcuts refuse to get pinned to Start Menu All app, then you want to count the list of apps you have installed on your Windows 10 computer.
To count the number of apps you have in the All app menu, open a PowerShell window, type the following command and hit Enter:
Get-StartApps | measure
This command gets the count of apps in the Start screen. Against Count, you will be able to see the number of apps. In my case you can see 129.
If your count exceeds 512, Windows 10 will not pin shortcuts of more apps. You will have to remove some or uninstall some apps.
To get all the names and IDs of apps in the Start Screen, you can also open an elevated PowerShell prompt, type Get-StartApps and hit Enter.
If you can uninstall some apps, you may be able to manually pin the apps shortcuts.
If this is not the issue in you case, then Office.com suggests a workaround.
Pin the Program to the taskbar
Simple yet effective. Manually pinning the program to the taskbar might be the best solution since it will remain pinned and can be accessed easily. Moreover, this option will make the things easier as you don’t need to search for the program in the All Apps list or the search bar.
Search for an existing document, spreadsheet or presentation and open it, once opened right click on the taskbar and select “Pin this program to taskbar”
In case of a new documents, all you need to do is right click anywhere on the desktop and select Microsoft Word Document or any other Office app with which you intend to create the document.
Once the file appears on your desktop right click on the taskbar and select “Pin this program to taskbar” just like how we did it in the earlier step.
Trust this helps.