What if KivyMD.DropdownMenu and Kivy.Labelbase don't work together?

Question

Python

I decided to add MDDropdownMenu, and I also added fonts before, now, after importing MDDropdownMenu, an error pops up:

...
ValueError: Lblt.font_style is set to an invalid option 'FFont'. Must be one of: ['H1', 'H2', 'H3', 'H4', 'H5', 'H6', 'Subtitle1', 'Subtitle2', 'Body1', 'Body2', 'Button', 'Caption', 'Overline', 'Icon']
...

What to do?