safari emptied cache cleared websites in pref/privacy unplugged router for minutes shut down imac..rebooted in safe mode...shut down..unplugged iMac and unplugged router again--held the power on my imac for 10 or seconds. plugged everything back in booted up...all is well.......??????--seems like holding the power button without any power to it drains chips and the secret.
Read up on how they work, clearing preferences and history is not going to get rid of them. It’s not something on your system.
This is a standard technology used across the internet to prevent spam users and bots. If you visit a website on a regular basis you won’t get them. If you clear your history and cache all the time, the website likely see’s you as a new user and will probably trigger it when you attempt to login.