This.

The EAD is on the list of acceptable documents. Take that print-out to the DMV, along with all your DACA approvals/documents, and ask for a supervisor if someone gives you trouble again. If the supervisor doesn't work, get them to call the office in Hartford. People who don't have visas or passports even (think some TPS recipients) are eligible for licenses. The clerks just aren't knowledgeable enough in immigration to know better.