My client had version 4.2.14; I upgraded their site to 4.3.6 today. Now both the left-side admin menu and the Member menu are messed up. I think it's the presence or lack of presence of a bootstrap CSS file, but I'm basing that only on having seen something similar in Joomla. I got an "error in the script" while using the upgrade link in the Admin Dashboard, so I took the upgrade kit, unzipped it, and did a copy-over the existing files to see if that would correct the problem. I just convinced my client to spend the money; I don't want them seeing the menus in this condition. Help! Toolie
Most possible it is browse cache issue. Some css files was changes during upgrade but your browser still use old css file. So please clear cache of your browser and test it again. Menu should looks properly. In case of you still has this issue please contact us in helpdesk https://www.amember.com/support/ We will troubleshoot it.