Quick update. Celerity mailed me 2 replacement DFO ends for their fiber optic cable. The cable ends I received had this little yellow sticker on them. The DFO ends that I currently have have a green sticker on them.

Long story short, the new ends did not work. Couldn't get a successful connection between TV and receiver no matter what I tried (regardless of resolution, content, USB power, etc.). Reverted back to the old DFO ends and the picture was back. Though the 4k issues remain.

I may have been unlucky and received a set of DOA DFO ends. Waiting to hear back from them.