Automatic link detection seems to be very sporadic on Evernote for Mac. I have noticed this since I installed it, and as of now I'm on 5.4.0 beta 2 and there doesn't seem to have been any improvement. I paste in URLs and they don't get turned into links. I highlight them and press control+k and instead of being smart like Gmail and turning what fits the format of a link into a link automatically I have to paste the link in again to the dialog that pops up to tell it where to link the text (which is itself a URL). Hopefully this makes sense, but basically it's WAY TOO MANY STEPS!