Did you notice that Logseq v0.2.8 (and a few earlier versions) only convert:
- ## with leading bullet into ## without leading bullet.
Logseq doesn’t convert:
░░░░- ### with indented leading bullet into ### without leading bullet.
The ## without leading bullet are correctly rendered as headings in other common Markdown editors. That also allow normal Markdown non-outline freeform text to be edited in Logseq. More about this in Allow non-outline (freeform) text, particularly Pihentagy reply in that topic on 15 July 2021 and Sabre23t reply on 17 July 2021 as of Logseq v0.2.5.