Self Funded Company Question

We need some insight...my husband had a major medical emergency earlier this year. He was fully covered at the time. I have found out that his company's health plan is self funded and BCBS is the administrator. Fast forward to several months later, his company abruptly closed, now filling Ch 11. His claims are high-dollar, about 900k and it took BCBS a while to finalized the claims due to the complexity of the claim. BCBS send payment over to the hospital, which they confirmed to me that the payment has posted. However, now, we are being told by his HR that they never funded the account for BCBS to issue payment and the HR is confused on how a payment was made. The BCBS reps told me that they would never send over payment if there were insufficient funds in the account and when they issued the payment, there was sufficient funds in the employer's account. So, my question is, can BCBS ask for that payment back from the hospital and then we will be liable that bill even though he was insured during the time of hospitalization? BTW...the EOB (which I saved) says we owe $0.