[Defender] IP Banning Whitelist Current IP not accepted

Hi,

The IP Banning section shows the message: We recommend you add your own IP to avoid getting locked out accidentally! Your current IP is 192.87.990.06.

But when I try to add 192.87.990.06 to the whitelist it is removed. A message pops up very quickly (too quick to read) saying something about it being invalid.

Also, according to a search for 'What's My IP' my current IP isn't 192.87.990.06 anyhow.

Therefore:

a) why would Defender say 'your current IP is xxx' but not accept it into the whitelist

b) why is it say my current IP is xxx when the internet suggests otherwise?

Thank you.