I'm not surprised that the no longer offer OON coverage.
tl;dr: they never wanted to pay the OON claims in the first place!
Insurance companies often won't even pay their portion of the OON when that is in your contract. I had a c-section at an in-network hospital (and the OB-GYN I chose was in network). But, a couple of months later I learned that, SURPRISE, the anesthesiologists at that hospital are all OON. Still, my insurance at that time was supposed to cover a very high percentage of it.
Insurance then played a paperwork game. They would deny the claim for improper procedure code, then the next time deny for improper dose code. They alternated these two "improper code" reasons for more than 2 full years . . . denying the claim more than a dozen times. This whole time, the doctor's office was also sending me bills for the full amount, which was thousands of dollars. I would call each time and patiently chat with people at both the doctor's office and insurance company.
Then, by chance, I saw in the newspaper that the state had fined this particular insurance company tens of millions of dollars for not paying OON claims they were supposed to pay. Now I knew that I did have some recourse: I finally got fed up and filed a formal complaint with my state's department of insurance (DOI), submitting copies of all of the paperwork I had on the claims denials and all of the phone notes I had (at that point I'd probably talked to the doctor's billing office and the insurance office more than 5 times each over the two years, each time being polite as I could be, and I took meticulous notes each time: date, time, name of person to whom I spoke, exactly what they said to me, in quotations.)
Insurance paid the claim less than 2 weeks after I was contacted by a social worker from the DOI who had reviewed my paperwork; at this point their new reason for why they hadn't paid before was that the doctor's office was mailing the claims to the wrong address all along. . . even though I had statement of benefits documents showing their detailed rationale for denying each of those claims (claims which they now say had been mailed to wrong address, what a joke.) It would be funny if it was not so ridiculous.
New strategy since then is that I just take a short cut on the phone with the insurance company the first time:
"I have made a good faith effort to follow proper procedures, and it is clear to me that the provider has also made a good faith effort. If this claim doesn't get paid this time, then my next step will be to file a formal complaint with the state's Department of Insurance." This language seems to get their full effort in paying the claim. Ridiculous that it has come to this.
Recently I had the problem where my work insurance refused to pay their portion of my urgent care claim while I was traveling on business. Again, round and round and round. My DOI threat seemed to fall on deaf ears (probably the insurance company doesn't operate in the state of the provider in this case.) Eventually it got sent to collections, and I wrote back to the collections agency that the remaining balance was in dispute. I sort of feel like a shit for doing this . . . it was only a few hundred dollars, and the doc is the one getting screwed.