There are several ways to (try to) fix this, and the most effective method is actually to free up disk space.
It doesn’t really matter what Windows 10 version you are running because similar problems have been reported on both old and new OS releases – for example, some users come across the same issue on Windows 10 November 2019 Update (version 1909), which is the latest version, but I previously experienced it in the April 2018 Update as well. If this bug occurs, the taskbar icons themselves are not removed, and you can still interact with them, only that instead of the icon what you see is blank taskbar space.
In addition to the desktop context menus that sometime appear under the taskbar, there’s another long-time bug in Windows 10 that keeps happening on various devices out there (and which I personally experienced a few months ago): taskbar icons go blank all of a sudden.
