Since yesterdays update the Content Manager tells or informs me that there 384 sceneries not installed. That is just about everything in my Community Folder…ie …all sceneries that I have bought and installed or downloaded from FlightSim.to and installed myself. Better still …the content xml in the local cashe folder shows these are installed and when I go to one of these sceneries in MSFS2020 its present and correct. I tell you what…These updates every 2 weeks and the new problems that manifest from these updates,leave me speechless! What’s up DOC? 
This has been acknowledged https://flightsimulator.zendesk.com/hc/en-us/articles/360016027399-KNOWN-ISSUES-Last-modified-Feb-16-2021-
OK…thank you for the info, and its not only me then. Well fortunately it has not screwed up the contents of my Community folder. 
Closing topic as it’s a duplicate of a known issue:
https://flightsimulator.zendesk.com/hc/en-us/articles/360016027399-KNOWN-ISSUES-Last-modified-Feb-16-2021-
You may also contribute to this existing topic:
https://forums.flightsimulator.com/t/addons-in-community-appear-as-not-installed-in-content-manager-after-updating-to-1-15-7-0-and-world-update-iv-although-they-are-installed/390491