I got 2 more orders that were done online and do not have custi_id:
ofggA5wcLpayBkJIEjHxV7V1TqBZY
OkDTVcGZQjoKuO8HVJMs6tTH25IZY
This is a known gap with the Online Store. If the seller doesn’t assign a customer at the transaction time (i.e., add a contact to a transaction explicitly), Square will automatically assign a contact (either new or existing) to that transaction. However, this automatic assignment will not be synced with Orders API today. That’s why you can see there is a contact assigned but you cannot get it from orders API (not synced).
The team is aware of this issue and working on a fix. Given the complexity of this fix there isn’t a timeline for an immediate fix. 
Any News on this? I really need to get this fixed!!!
At this time there isn’t any updates on this.
Can we please escalate this issue, very unhappy customer here!
I’ll be sure to share your request to the API product team.