[SOLVED] menu item creation - Invalid field: Page Class

Not related to FC.
Apparently Joomla does not accept class names beginning with numbers.

When creating a menu item of type Flexicontent, it is not possible to store a page class.
No matter the value added to that field, the followjng error is shown:

This does not happen when menu items of other types are created (for instance, Joomla single articles), therefore I am led to believe that the error is FC-related.

Environment:
Joomla 4.4.2
FC from Github (as of 2024-01-22)
PHP 7.4.

 

thanks for return