Submit SPKAC with subject to standalone ADCS

Microsoft's documentation suggests that it's possible to include a subject with a SPKAC CSR - https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-wcce/f88ecd9a-26bb-4b74-a471-4c46e773f75b.

However, when passing the RDN attribute with certeq on Windows Server 2016, the submission fails:

> certreq -Submit -attrib "CertType:server\nChallenge:$Challenge\nRDN:CN=Bob" -Config $Config C:\path\to\spkac.req
> certutil -Resubmit $RequestId

CertUtil: -resubmit command FAILED: 0x80094001 (-2146877439 CERTSRV_E_BAD_REQUESTSUBJECT)
CertUtil: The request subject name is invalid or too long.

What is the correct way to submit a SPKAC with a subject to a standalone ADCS using certreq/Powershell?