Normally, you can select multiple notes from the list using Ctrl+Click or Shift+Click. After you create a new note, the multi-selection mode becomes permanently active, as if you were pressing Ctrl key. Solved only by restarting the app.
Please see screencast where I reproduce the issue: http://bit.ly/2WzDi3b
I can replicate the issue.
Can't quite seem to replicate the issue.
I did however got the same bug by doing something slightly different:
I can reproduce this on Linux Mint 18
Still an issue on Linux Mint 19.