SUMMARY

Starting with Krita 5.2.0 to the newest stable release (5.2.4), modifying a filter engine brush with a new filter will crash Krita. Tested on Windows and Android.

The crash does not happen on 5.1.5.


STEPS TO REPRODUCE
1. Choose a filter engine brush preset, such as "x) Filter Blur"
2. Open Brush Editor, click on Filter, and choose a different filter, for example, Color to Alpha.


OBSERVED RESULT
Upon choosing a different filter, such as Color to Alpha, you will notice the Filter Settings did not change to display the chosen filter's settings. The old filter settings are still showing.

If you try to change anything in the Filter Settings, such as what-is-now-the-old "Horizontal Radius," Krita will crash (which would make sense, since Horizontal Radius is not a setting that exists with Color to Alpha, so this probably confuses Krita).

EXPECTED RESULT
Krita should show the new Filter Settings upon selection of the desired filter and also not crash. 

The CORRECT behavior can be achieved if you go back to Krita 5.1.5.


SOFTWARE/OS VERSIONS
Windows: Krita 5.2.0 to 5.2.4
Android: Krita 5.2.3, arm64 apk