Wagtail Admin ,checkboxselectmultiple Not Saving Data

@register_snippet class Numbers(models.Model): number = models.IntegerField() class State(models.Model): state = models.CharField(max_length=100) number = ParentalMany

Solution 1:

Models using ParentalManyToManyField need to inherit from modelcluster.models.ClusterableModel.

from modelcluster.models import ClusterableModel

classState(ClusterableModel):
    state = models.CharField(max_length=100)
    number = ParentalManyToManyField(Numbers)

Also, make sure you have django-modelcluster version 4.0 (or above) installed - older versions had a bug preventing m2m relations in inline objects from working.