Office Applications Uninstalled in the Terminal Server

First off,  Are you utilizing the Click 2 Run service?   As in do you have the proper licensing in place or are you just using a volume licensing for your users?  

I could see the system noticing there are different version of office installed and uninstalling one or the other because of what you have installed.  Maybe these different versions are not compatible.  https://support.office.com/en-us/article/install-and-use-different-versions-of-office-on-the-same-pc-6ebb44ce-18a3-43f9-a187-b78c513788bf    see the link for more information. aljafar0622