How exactly are you creating the menus? Have you followed the guide found here?

attractabrennan

Hello,

This is a general topic for general discussions.

If you have a problem with any of our themes, please create a new topic in appropriate forum group, and we'll help you. If the problem occurs with default WordPress theme, then it means that there is something with your WordPress install.

Hello, if this is WordPress problem
1. Do you have large menu items?
2. If you do, try one of the following
a. edit wp-config.php, add the following

b If 2b doesn't work, contact your web host, confirm and ask them if you had Suhosin installed and to add the following

c. If you don't have Suhosin, ask your web host to increase memory, however this is only works on Dedicated and the web host usually asking for upgrade fee.

split your menu into 2 separate menus and then just display them next to each other is better way

3. If you do not have large menu items, just few items
a. deactivating all plugins to see if this resolves the problem? If this works, re-activate the plugins one by one until you find the problematic plugin(s).

b switching to the default theme (Twenty Elevent) to rule out any theme-specific problems?