I just played a match with Prove Thyself equipped. Usually the perk icon lights up and I get a small blue icon that shows it's affects are being applied. There was none of that this time. See attached video clip.
Thank you for taking the time to report this issue, we are forwarding this to the team for their review.
Hey I also had that bug and it happened twice. I believe that it does not work after someone dies. That is just a theory because it stop working after one of my teammates died and in your clip I noticed that too.