Created attachment 146456 [details] screenshot of callout Open Draw and draw a legacy Callout, that one from the toolbar "Text", not the custom shape. Notice, that the "elbow" of the tail has got a marker too, although it is not drag able. Notice, that you cannot size the callout, where the tail meets the rectangle. That is because there is a marker of the tail on top of the marker of the rectangle. All points of the tail have got markers, but only the end of the tail should have one. [Using the Position&Size dialog to change the kind of callout will crash. I'm going to write a separate issue for that. If I fix this issue, LibreOffice will still crash, thus the crash is a different problem.]
Proposed patch is in https://gerrit.libreoffice.org/#/c/63120/
Regina Henschel committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/+/a35e7f38942ca3cc3b277692fae86d0787db934a%5E%21 tdf#121287 Use correct markers on tail of legacy callout It will be available in 6.2.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.