Check your console (F8), you’ll probably be getting a message like this near the top when FiveM is first starting up:
lambdamenu.asi - this ASI plugin does not claim to support game build 2372. If you have access to its source code, add
FX_ASI_BUILD 2372 dummy.txt
to the .rc file when building this plugin. If not, contact its maintainer.
FiveM now requires that .asi plugins explicitly state they are compatible with gamebuilds from 2189 and up. You can add this yourself instead of waiting for the maintainers to update the plugin: