Customer id = 0 in order table (in some instances)

Hello. i really hope i posted this in the right category.
my problem is that what seems like random. no customer id is stored in the order. well. a "0" is stored wich indicates a guest. but guest login/buy is disabled.

i have previously activated the guest, and i have had i think 2 plugins associated with that feature. but the plugins are removed. and the feature has been disabled.

most of the times a customer is created, but not "connected" to the order via the customer_id. on some instances. the order has no aparrent customer at all.

im looking for a fix or some code to prevent this.

No OC version posted. However, are you still able to see the customer's address in your order? If so, also please post your error / server access logs regarding the latest order created. You can also enable the debug mode in the payment extension module you are using from the OC admin.

In addition, if you do see the customer's address in the order, ensure to use the following fix: https://github.com/opencart/opencart/issues/7317 .