Tried bannering in some PCs that belonged to a 'defunct' banner, and it would not allow me to.
PCs were part of the Lathanderite faction, which cannot banner in new members after the loss of Prior Blake.
Got a message when I used the banner token on them
"Already belongs to another banner" or something.
Can't imagine this is intentional.
DMs fix that.
Are you telling your fellow DMs to fix that or are you telling me to get a DM in the moment to fix it on the spot?
He's saying you need a DM to do it. Right now it's not scripted so yo ucan do it on your own afaik!