We have the same problem - it is a huge issue for builders. Here's the work-around we came up with:
1. We created an expense account called "COI"
2. We created a new non-inventory "Product & Service" called "COI" and linked it to the "COI" expense account
3. We need to track general liability and worker's comp, so for each vendor who we need to track insurance, we created two "Purchase Orders" - we used the "PO Number" field and labelled one "Gen Liab" and one "Workers Comp". We dated the PO the date of the vendor's policy expiration and linked it to the "COI" Product & Service item and gave it a zero $ value.
It's not perfect and certainly not as easy as in desktop, but at least now we can run a report for "Open Purchase Order Details" and see when our vendor's policies are expiring - when we get a new COI, we update the PO date to the new expiration date.
Also, we don't use "Terms" for most of our vendors, so we created a "Term" called "On-Site" to use to designate which vendors we need to track insurance (for us, our insurance company requires that we have a COI for any vendors who are on our job sites). In desktop, we were able to use the "Vendor Type" field, but as you know, QBO is terrible for builders and took away so much functionality that was available in desktop.
I hope this helps and please let me know if you need clarification of any steps. I hope you find this helpful too.
