Hand up here - a few years ago now.
On Exchange in Devon, level 7 at the time hoping to get to 6, and a well know SW Peninsular Assessor watching me (with sharpened pencils at the ready !).
Tough fiery match and I am doing pretty well with usual problem areas ok e.g. spotting first offences, keeping players on their feet at tackle / ruck, managing offsides with open stance, etc. Control ok, communication ok, cool/calm/collected (this is know in assessor trade as marking the C's !).
Then ball passed out to red wing on blue's 22m line, he fumbles it, it goes forward and as I am so wound up and adrenelin full, out goes my arm for advantage blue anticipating (or 'seeing' a knock on, tackler bounces off him at hips, he juggles it, and juggles it and juggles it and as he gets control I blow my whistle ! Knocked on in contact my call, scrum blue. No one comments and we finish match. I am pleased with my performance and skippers seem happy and even coaches. Shower, change and go to clubhouse for de-brief.
It starts ok, complimented on speed around pitch for man of my age and stature (think mid 40s Teletubby), good empathy and control, etc etc. I am relaxing. Mistake, as he then asks me about a critical decision - ooops, at level 7 and higher this is a referee 'danger signal' - I am on full alert.
I am asked to recall the events above - it could have been a match winning try in a low score close match, but it was a knock on I say. Did the ball touch ground says assessor, did it hit an opposition player, was it re-adjustment, was it deliberate 'pat' forward ? I am convinced in my own mind that I saw a knock-on (impact of tackler was quite hard but he was powerful lad on red wing) until the penny dropped as assessor sat there silent.
So key exchange report with a 'critical' on it, so never did make it to level 6 !