How to use Embedded Document in bulk insert

I'm using this model

class Schedule(EmbeddedDocument):
    scheduleId: StringField(required=True)
    detail: StringField()
        
class AccountBalance(Document):
    memberID = StringField(required=True)
    schedule = ListField(EmbeddedDocumentField(Schedule))
 
 array = []
for index, row in df.iterrows():

    # handle schedule
    schedule = Schedule()
    schedule.scheduleId = "1234667777"
    schedule.detail = "some random detail"

    payload = {
        "memberID": "98765",
        "schedule": schedule,
    }

    array.append(payload)
    
 person_instances = [TrialBalance(**data) for data in array]
 AccountBalance.objects.insert(person_instances, load_bulk=False)

If I comment out code for schedule class (Embedded document), the code works like charm but when I try to run this code, it throws an error
The source SON object needs to be of type 'dict' but a '<class 'str'>' was found

Can someone tell me how to use the embedded document in bulk insert or how to fix this error??

The issue provides no repository file or test to start from. Reproduce the shown AccountBalance.objects.insert(...) path with the Schedule and payload examples, then use the embedded-document and bulk-insert behavior as the completion check.