I had this same problem and figured out that admin menu has some strange ways of getting things to work. I had the same issue with another plugin and admin menu prior as well, when I updated that plugin. Since both do the same thing I'm guessing it was the update itself that was the issue not the adminimize.
Both plugins have backups so back them up and delete them. Reinstall adminimize and import settings. Then install admin menu and first try only changing the menu that was having issues and I'm pretty sure it will work. If it does go ahead and install the import file.
I know this sounds stupid and isn't much of a developers answer, but it worked for me both times. I'm not really sure why it worked but only thing I can think of is the plugins are fighting over who does what.
Anyway, if that doesn't work and you want to keep adminimize, drop admin menu and install admin ui customize.
The developer has pretty much made plugin for everything you'd want to change in the backend. Some of them are still a little buggy, but he's constantly working on them and will help you right away if you need it. It takes care of the toolbar, admin menu, dashboard, and pretty much the entire admin.