Using InTune for BitLocker enabling TPM+PIN+USB

This is not supported, take a look at the documentation:

https://docs.microsoft.com/en-us/windows/security/information-protection/bitlocker/prepare-your-organization-for-bitlocker-planning-and-policies#bitlocker-key-protectors

PIN A user-entered numeric key protector that can only be used in addition to the TPM.

Additionally, the supported authentication methods are listed too:

TPM only
TPM + PIN
TPM + Network key
TPM + startup key
Startup key only