Error driver not installed for custom driver

[Oscar4596]

Hey guys!
I'm getting a driver is not installed error when trying to use a custom driver for molecule.
When I run:

$ molecule drivers                                               
──────────────────────╴
  custom_driver
  delegated
  ec2

I see the driver installed, but when running molecule test or even molecule test -d custom_driver I still get the error. I think I might be missing something in the custom driver configuration towards the latest updates in molecule.
I install the driver using pip from a private repo.
The validation for a driver is made in this line.

My env:

molecule 5.0.0 using python 3.9 
    ansible:2.15.1
    custom_driver:2.2.4.dev9+gd26bfb5 from molecule_ec2_bundled
    delegated:5.0.0 from molecule
    ec2:0.4 from 

I'd appreciate if you could help me, and thanks in advance!