After a very long P2V process, I booted up the new VM and was greeted with the following error:

The parent virtual disk has been modified since the child was created.

Upon which, the VM would not power on. After waiting on a 12 hour conversion, this is a depressing error to receive. Luckily, it is fixable. Using KB 1007969, the vmdks can be edited to fix the mismatch.

Essentially, you have to rebuild the parent-child chain within the VMDKs. The KB does a very detailed job of explaining what to do, but I will note to make sure you’re changing the parentCID of the file once you modify and not the CID itself, and I’d recommend commenting what you change in case you need to revert. After getting the VM to power on, be sure that the VM behaves in an expected state.