Device storage showing incorrect data volumes?

[AC Question]

I'm receiving the warning that my device storage is almost full. The storage analyser/manager says:
- there is only 0,5 GB of free space left
- apps are using 16.9 GB of space (while the MAX device storage in reality is 16 GB, 5 of which is dedicated to system memory). Something must be wrong here

I only have 2 apps taking up a lot of space:
- my newspaper app, holding the downloaded newspapers/magazines (currently taking about 3.6 GB of the device storage
- Spotify - BUT, Spotify is set to store offline music to the SD card. Indeed, in the storage settings, I see that 7.59 GB of the SD card is used, so this must be the Spotify music, as I have nothing else storing to the SD. Yet, in the storage manager, it says that Spotify takes up 6.92 GB of the device storage.

So, could it be that the storage manager is erroneously counting the Spotify offline music towards used volume on the device storage, even though in reality that is being save to the SD card?

When I connect my Samsung Galaxy A5 (2016) to my pc and look at the volume usage in explorer, it also shows that only 0,5 GB of the device storage is unused / 10.5 GB of 11 GB is used.