SUMMARY
kmail2 is crashing when moving mails to other folders. Same for drag & drop as via filter.

STEPS TO REPRODUCE
1. Choose a mail and move it with drag'n drop or paste and copy from the menu to another folder.

OBSERVED RESULT
Kmail2 is crashing

EXPECTED RESULT
Copy/move mail to the target folder

SOFTWARE/OS VERSIONS
Operating System: KDE neon 6.0
KDE Plasma Version: 6.1.2
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.0
Graphics Platform: Wayland
Graphics Processor: Mesa Intel® HD Graphics 620

---------------------------------

The following output appears when the application is started in the terminal:

On the terminal following output 
org.kde.pim.akonadicore: couldn't find index of unlinked item  816138 119 -1
ASSERT: "false" in file ./src/core/models/entitytreemodel_p.cpp, line 1258
*** KMail got signal 6 (Exiting)
*** Dead letters dumped.
/tmp/messageviewer_BqBiIw.index.2 was not removed .
/tmp/messageviewer_bzgalz.index.3 was not removed .
/tmp/messageviewer_DlcMNL.index.2 was not removed .
/tmp/messageviewer_OnayTt.index.2 was not removed .
/tmp/messageviewer_reCRzz.index.4 was not removed .
/tmp/messageviewer_tXTDpw.index.3 was not removed .
/tmp/messageviewer_uMKoON.index.2 was not removed .
/tmp/messageviewer_utWcht.index.3 was not removed .
/tmp/messageviewer_XzbfXV.index.3 was not removed .
/tmp/messageviewer_zKrEsq.index.4 was not removed .
/tmp/messageviewer_BqBiIw.index.2 was removed .
/tmp/messageviewer_bzgalz.index.3 was removed .
/tmp/messageviewer_DlcMNL.index.2 was removed .
/tmp/messageviewer_OnayTt.index.2 was removed .
/tmp/messageviewer_reCRzz.index.4 was removed .
/tmp/messageviewer_tXTDpw.index.3 was removed .
/tmp/messageviewer_uMKoON.index.2 was removed .
/tmp/messageviewer_utWcht.index.3 was removed .
/tmp/messageviewer_XzbfXV.index.3 was removed .
/tmp/messageviewer_zKrEsq.index.4 was removed .
KCrash: Application 'kmail' crashing... crashRecursionCounter = 2
Abgebrochen (Speicherabzug geschrieben)