Cubase 8.5.3 - pool referring to removed files

Hi, another issue with my fresh 8.5.3 update (which wasn’t present in the 8.5.2 version, at least on my system).

After I’ve been working on a project for a while and adding/removing files either via pool’s import routine, or simply by dragging and dropping, the issue happens where the pool suddenly keeps a “record” of the files I removed, as if they were still present in the project, and doesn’t allow me to “remove” them again via right-click dialog (remove unused media). Basically - a “ghost” list of sorts which can not be removed. The only way I found to solve that is to re-load the project, which is annoying and to me looks like a bug.

Picture attached.

Windows 10 Enterprise LTSB x64, Steinberg UR22 (mk1), Intel i7 7700K, Asus motherboard, latest bios