Sorry about that; I'll upload the macro itself next time!
After lots of testing, this turned out to be specific to the Notion web app itself so not an issue with KM, but thanks!
(I've got some additional problems there because Notion applies automatic Markdown formatting and I'll have to write something with regex to prevent triggering auto formatting but that's a different issue entirely.)
If you don't mind the formatting in Notion but that's what is messing up your path in the "Open" step, do the "Copy" then regex the System Clipboard to get the cleaned-up version for your "Open" action.