Having had three opportunities in my life to diagnose this exact problem and then successfully resolve it by turning off the WAF rule (see my top level comment) - I don't know you or your work history, but trust me, the author is much closer to the truth here than you are.

edit: Also, someone commented here "it was an irrelevant cf WAF rule, we disabled it". Assuming honesty, seems to confirm that the author was indeed right.