I have copy inherited the purchase.order model in my custom module, and named the model purchase.order.copy.

classPurhcasePi(models.Model):
	​_name="purchase.order.copy"
	​_inherit= ['purchase.order','mail.thread', 'mail.activity.mixin']
	​_description="Purchase order copy"

but when I try to create and save the record, it loads forever saying "Take a minute to get a coffee, because it's loading".

it doesn't give any error in the log file or in the front end.