Github seems to have file size limits, so this is a truncated (to the last ~115,000 lines) of the log file.
Steps I've taken.
Registered gpgol.dll via regsvr32.exe
Outlook no longer prompts for which key to use to sign a message, instead assumes a message is empty.
One thing to note, a recent recipient did not install his public key and so incorrectly assumed that the message was empty. It's been this way every since. Unsure how/why that affected my installation.