How does this work out mathematically?

The phone can barely have two running applications simultaneously after 4.3. Doubt it was to do with the update, and more the complete lack of space. But what is taking up the space? Any tips?

Storage space shouldn’t affect your ability to run multiple apps really (unless you are completely out) - RAM does that.

Maybe it is failing to count Android apps - do you really have 0?

It seems to me like a bug. I have SFOS 4.3 and it shows me 0 for android apps and apps data. And summary is less than used space…

So maybe we are back in time?

When executing jolla-settings with strace, there is visible that this process (running as defaultuser) has no acess rights to /home/.android/data/app:

[defaultuser@Xperia ~]$ strace -f jolla-settings
[pid  9676] faccessat(AT_FDCWD, "/home/.android/data/app", R_OK <unfinished ...>
[pid  9676] <... faccessat resumed>)    = -1 EACCES (Operace zamĂ­tnuta)

so, it explains why Android applications are not counted…

[root@Xperia ~]# du -h -d 0 /home/.android/data/app
1.8G    /home/.android/data/app