SUMMARY I've been experiencing this for quite a while but never found a way to reliably reproduce it, so I'm reporting it now regardless. The closest thing that I found that maybe causes this to be reproduced is to not have Kontact/KMail active, but I can't confirm this. Anyway. If I create a filter that first moves an email to a folder and then tags it, it doesn't always apply the tag. Similarly, if I create a filter that first adds a tag to the email and then moves it to a folder, same result. Tags apply fine when there's no moving being done. STEPS TO REPRODUCE 1. Create a filter. 2. Add a rule to apply tag. 3. Add a rule to move to a different folder. OBSERVED RESULT Email gets occasionally tagged. EXPECTED RESULT Email should always get tagged. SOFTWARE/OS VERSIONS Operating System: openSUSE Tumbleweed 20201009 KDE Plasma Version: 5.20.80 KDE Frameworks Version: 5.76.0 Qt Version: 5.15.1