Created attachment 138711 [details]
Steps to reproduce:
1. Place the cursor at the beginning of the third line ( before "P2" ).
2. Press backspace twice to remove the bullet and connect two lines.
3. Ctrl + Z
Two lines split and the bullet is hidden. One more step is required to recover the bullet.
Two lines split, but the bullet reappear.
CPU threads: 8; OS: Windows 6.2; UI render: 預設;
語言地區：zh-TW (zh_TW); Calc: group
Confirmed with LO 220.127.116.11 & 3.3.0 / Windows 7.
Crashes in 6.0beta1, 6.0beta2 & 18.104.22.168 if OpenGL is enabled, opened bug 114736 on that.
Mark Hung committed a patch related to this issue.
It has been pushed to "master":
tdf#114732 backspace can only make bullet invisible.
It will be available in 6.1.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.
A polite ping to Mark Hung: is this bug fixed? if so, could you
please close it as RESOLVED FIXED ? Thanks