• list1
• aaa

• list2
• bb

The list is split into two lists

Suppose you use “Text” editor to remove the intervening </ul><ul>. The moment you switch back to “Visual” editor, WPress algorithm will detect the removal, and convert it to

• • list1
  • aaa

• list2
• bb

— The solution ..

1. switch to the Text editor, copy the list source code to notepad, clean up slowly, while keeping the bpost intact.
2. Once done, switch to Visual and remove the entire original list
3. switch to Text to paste the list source code from notepad
4. when you switch back to Visual, the WPress algorithm sees a brand new list and does nothing.