Steps to replicate bug

Set up a fresh server and add b_channel_join_ignore_password to the channel admin channel group.
Create a new channel with a random password.
Give the new identity channel admin in the new channel
Make a bookmark for this new identity with the starting channel as the new passworded one and leave the password field blank.
Connect via the bookmark

Result

Even though you can bypass passwords on that channel and you can enter it without "knowing" the channel (even if you clear cached ch passwords) you cannot connect into the channel (even though you are allowed entrance to the channel) and instead are sent to the default server channel.

The b_channel_join_ignore_password permission is a very useful permission and lets channel admins and others get into channels even if someone else changes the password, but as I have just explained if the password is changed and you do not have the specific password in your bookmark it will not send you to your desired channel upon connecting.