I have the same issue and tried everything you said, and even restart my computer before download. But still can't place a joint anywhere.
I just uploaded a new Windows version, which should hopefully fix the issue. Can you please follow these steps and the let me know if it worked or not:
(You might not need to do all three of these steps - do them one at a time, try again and stop as soon as the editor works again.)
1. Go to C:\User\YourUser\AppData\LocalLow\Keiwan Donyagard\Evolution and delete the CreatureSaves folder.
2. Open regedit and go to HKEY_CURRENT_USER\Software\Keiwan Donyagard\Evolution and delete the entries that begin with "LAST_CREATURE_DESIGN_KEY" and "DID_MIGRATE_CREATURE_SAVES_KEY".
3. If both steps above didn't fix the issue yet, delete the whole Evolution folder in your registry using regedit.