Microsoft released two out-of-band security updates for remote code execution vulnerabilities in the Windows Codecs Library. Instead of delivering these security updates via Windows Update, Microsoft is rolling them out via auto-updates on the Microsoft Store. Microsoft did not explain what Microsoft Store apps would be updated to resolve the vulnerabilities, leaving users in the dark as to whether they were affected and patched by an update. Some users are having problems installing the update via the store, as shown in the tweet below.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10s-microsoft-store-codecs-patches-are-confusing-users/