SUMMARY
When doing an initial analysis of a folder, filelight will display a 5-level depth analysis of the space use in the pie-chart view. However if clicking on one of the outer ring elements and navigating back with the « Up » button, you never get the 5-level depth.

STEPS TO REPRODUCE
1.  Start filelight and analyze your home folder
2.  Click one of the elements in the outer/5th level ring to dive in 
3.  Click the « Up » button 5 times

OBSERVED RESULT
Single ring / single depth pie chart analysis of the home folder.

EXPECTED RESULT
5-level deep analysis of the home folder, same as after the initial analysis.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.101.1
Qt Version: 5.15.7

ADDITIONAL INFORMATION
Running the HEAD of the master branch as of 2023-01-07, commit 902a954.
I have a big home with > 600k files and > 600 GiB, it’s not reproducible on a second smaller user home on this machine.
The issue happens even when analysing as smaller folder down the tree in the big user’s home.