So I also had this problem. My Evernote no longer crashes but the open in a new tab simply no longer works. But I did find a workaround posted back in 2016. I also use a Mac, High Sierra.
- open the notes you want to have pinned to the tab bar
- on the menu bar click on "window"
- click on "merge all windows"
- repeat until all of the windows are pinned onto the tab bar
Workflow is so much better when notes are pinned to the tab menu.