Hey there Andrea  

Paul here from Intercom Support!

There isn't currently a way to insert an image between list items, however, what you could do is remove the list formatting (by backspacing) and write out the numbers/bullets manually. Then you'll be able to insert images between the lines.

That said, our product team is exploring expanding the article editor's capabilities, so I'll let them know this is a feature you're interested in! 

We have no issues inserting images inbetween numbered lists or bullet points. I just either write out the lists, then insert inbetween the lines. I use Shift + Enter for added spacing which can prevent a new numbered line from being created by accident.

See below an example:
 

However, the ability to insert a callout in lists we’re unable to do either and would have to use Paul’s work around.