m15 R6, PCR[7] not bindable

Hi,

I recently got an m15 R6 and I'm trying to get BitLocker set up to use PCR[7] for its validation profile, but it isn't able to bind. In Event Viewer, under Applications and Services Logs > Microsoft > Windows > BitLocker API, there are two recurring events:

Event 834 (Information):

BitLocker determined that the TCG log is invalid for use of Secure Boot. The filtered TCG log for PCR[7] is included in this event.

and

Event 839 (Warning):

BitLocker cannot use Secure Boot for integrity because the TCG Log entry for the OS Loader Authority is invalid.

The signature contained in the EFI_SIGNATURE_DATA structure from the OS authority event could not be found in the verified certificate chain for the boot loader.

So far, I've tried clearing the TPM, resetting the BIOS, re-flashing the BIOS, resetting all Secure Boot keys through the UEFI setup menu, restoring to the factory image, and reinstalling Windows from the standard installation media, and nothing has changed the binding status of PCR[7]. I have also tried using tpmtool.exe, tpmdiagnostics.exe, and TCGLogTools to find more information, but I haven't gotten anywhere yet.

The only possibly relevant information I can find is from a log exported and parsed with TCGLogTools, which I have attached here. Interestingly, the "SignatureData" from these two events correspond with the last entry in the forbidden signatures (dbx) database in the same log file, seen here. I could be misunderstanding how this works, but wouldn't that prevent the OS from booting? 

If anyone here is more familiar with Secure Boot troubleshooting than I am, I would greatly appreciate your input. In the worst case, this might only be fixable with a BIOS update from Dell, so I am hoping I can resolve it before getting to that point.

Thanks in advance,

Joel