We have been alerted to errors when ordering SSLs.
Two specific errors are being returned by Sectigo and this appears to be due to an order build issue on their systems. We are placing the order with them as soon as payment is complete and they are returning an order ID but then not building the order against it, either with an invalid product, or unallocated credit error.
We have seen this before and it was quickly fixed within their API and have raised the issue with them again. Due to the weekend, we are unlikely to hear from them but will chase on Monday.