Nope, it's a must.

I encountered this after 2 rejections - and we did have the 1095-A form, it was a different issue about trying to figure out how to claim 0% for the independent child still on parents insurance. I even spoke to an IRS ACA specialist. They really need to contact the state to get that form because it will not be accepted by e-file and is unlikely the IRS will accept as even a paper return without the info from that, because they are inextricably attached if you have an ACA health plan. I don't agree with that fact the ACA is tied to tax filings, but we have to follow the law. 

Do note the 8962 must be filled out correctly too, if you are able to obtain the 1095-A, make sure the 8962 shows up as a form in use before you try to e-file. It will pass the final review without it but the IRS won't accept it unless you have both the 1095-A and the 8962 as part of the tax form.\

I was about to do a separate doc to attach as explanation - which might have worked in my client's case, but I don't think that will work in yours as the numbers of plans avail and their advance payment is crucial to their debt or refund.