Cert Renewal Fails Due to CAA mismatch, Can't Authorize Additional CA

I recently received an email that AWS failed to renew certificates for subdomains whose DNS is through Route53. The root domain uses a certificate from another authority. There is a mismatch in the CAA records because the current record is for the root domain which uses a certificate from the different certificate authority, so AWS fails to renew. Fine, I thought... I will just add the appropriate record to additionally authorize AWS.

Now, research tells me that you cannot list multiple authorities in a single CAA record, and that the appropriate process is to create multiple CAA records. But:

• Route53 errors when attempting to create another CAA record for the root, complaining the record already exists (research says this actually should be valid).
• Route53 errors when attempting to create a CAA record for the specific subdomains under the AWS certificate, complaining that the subdomain.example.com CAA is in conflict with example.com CAA (research says this actually should be valid).

So it seems that AWS Route53 implementation of CAA is bugged and it is not possible to renew my AWS certificates unless AWS can alter their own code. Please advise.