Collapsed Field is not showing in form when using collapse class in django admin fieldsets

[mahbd]

While I use collapse class, no show button not fields show up. Please see image for clearance

Django==3.2.8
python==3.10.0

settings.py

INSTALLED_APPS = [
    'admin_interface',
    'colorfield',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'CheckAdmin',
]

models.py

class Check(models.Model):
    name = models.CharField(max_length=255)
    name1 = models.CharField(max_length=255)
    name2 = models.CharField(max_length=255)

admin.py

@admin.register(Check)
class CheckAdmin(admin.ModelAdmin):
    fieldsets = (
        (None, {
            'fields': ['name']
        }),
        ('Optionals', {
            'classes': ['collapse'],
            'fields': ['name1', 'name2']
        })
    )

Actually I found this problem when using django-admin-508 in another project. To be sure that the issue is being caused by django-admin-508 I created new project and found it is being caused by django-admin-508.

Note: Around six month ago when I was trying to use bootstrap4 in admin panel I faced same issue. So, I guess it is CSS related issue

[jorgegonzalez]

Thanks for the report, I'll look into this soon.