Cannot add item to banned host list/Proxy

[PotatoCarl]

Hi,
I have a (longer) list of banned IPs for the ACLs in the proxy, as it seems to be difficult to insert a "whitelist".
That means that the network 192.168.1.0/24 is allowed and the banned hosts are not.
However, recently I cannot add any IP to the list anymore. Whenever I press "apply" there is a "validation error".
I assume actually that the string in the script might be too short, but that is just guessing...

Any ideas how to circumvent this?

Best regards