fail2ban

if i try to ban ipv6 i have this error "ArithmeticError: Bit shift by negative number (Address.php:871)"

Good morning, I've read a lot about 'problems' with Fail2ban sals filter, and the "solution" was to use postfix[mode=auth], but in my case it doesn't work. After a little troubleshooting, I have found this inconsistency beetween what is showed on LoBbrowser and what I found on maillog...