Confusing interaction when typing leading * for headings when org-hide-emphasis-markers is on

[Stig Brautaset <stig@brautaset.org>]

Hello,

I've got =(setq org-hide-emphasis-markers t)= in my config, and 
it's mostly great but it does confuse me when I manually start 
sub-sub headings. (Which perhaps is a silly thing to do, but 
getting over muscle memory is hard to change.) After typing the 
third =*= (and on any subsequent ones typed) the first and last 
asterisks are hidden and the remaining appear bolded, until I type 
a space when what I'm typing is suddenly recognised as a heading 
and snaps back to displaying all the typed asterisks as expected.

I couldn't figure out how to post a video, so visually, here is 
what I see. One character typed on each line (comments after =;=):

: *
: **
: *      ; this is in bold
: **     ; this is in bold
: ****   ; asterisks no longer bold after typing a space

I tried adding an asterisks to the BORDER characters in 
org-emphasis-regexp-components, but that didn't seem to help.

PS: I realise that ironing out all visual niggles here is perhaps 
not possible, and perhaps me just learning to use the Org 
functions for inserting headings would hide the problem from me, 
but I decided to report it in case it turns out to be simple to 
find an acceptable fix for someone.

Stig
--
; GNU Emacs 27.0.50, Org mode version 9.1.3