by Chris McIntosh.
This is still a problem with Bitnami Moodle 2.6.2 (I think, can't find the exact version number for some reason). I installed the newer version (2.6.3) locally and did not have this problem.
The workaround in the link works, but you have to go to Administration > Site administration > Plugins > Blocks > Manage block
Click the Padlock icon to unprotect the navigation block so you can delete it and re-add it.