received check and EOB from insurance, but 2 months later no bill from provider

I live in PA and had an employer-provided high option PPO plan through Blue Cross. This plan was active up until September 1st (I have since then switched to a marketplace HMO with the same insurance company).

In early July (so still covered by the PPO) I had my regular checkup with my in-network OB-GYN and after discussing my family history (multiple female family members with breast cancer) she recommended I do a genetic test for breast cancer. She made it clear to me that I needed to be detailed in my written family history section that I submit with the test to make sure it was covered by insurance, which I then did. I submitted the test and received the results back in mid-July.

On Sept 7th, I received a statement in the mail from the insurance company with a check for over $700 and an EOB (“THIS IS NOT A BILL”) that said that the test was out-of-network, therefore billed as coinsurance, and said that I should be prepared to pay $1200 out-of-pocket to the provider for the test.

My stomach dropped and I immediately scoured my email inbox and spam: no word from the testing service other than my results. I logged into the account with the testing service and tried to find any messages about billing but again, nothing. I’ve thrice now (again this morning) looked up my account with the testing service provider, searched for my Case ID in their “Pay My Statement” portal and they have not posted a bill or contacted me in any way for collection. After perusing their website, they say that they “accept all major health insurances” but don’t list my specific regional one. They also say they offer income-based payment plans which I think I would qualify for (I make ~$30,000 a year) to at least make the test more like $200 and not $1200. However, if it has already been billed to insurance, I am not sure if that’s still an option.