Using Shift-Opt-(drag-select-text) works to select text in the expected way until you end the drag-select, then it reverts only to the first line in the selection.
Context: I keep a daily log and copy/paste into Slack for daily status. The bullet points don’t play well with Slack. I experimented to see if I could mult-line-select similar to Xcode, leaving out the bullet points. I was delighted when it seemed to be working on my bullet list until I let go of the drag. 
Indeed, unfortunately this type of selection is not compatible at the moment with the internal model of Agenda, sorry.
Secondary to this, I’d love a way to copy the note contents as Markdown. Incompatible elements could be inserted as description placeholder text or dropped entirely. It would greatly improve my workflow.
Does Edit > Copy As > Markdown not work for you?
Is this relatively new or did I just keep missing it?
Hahaha, it’s been there from day one 
(sigh) I swear I’m technical.
so am I, and no need to beat yourself up, I wrote this app and still encounter places where I discover we already did that 