Wvw has been bugging out, no idea what causes it but probably something to do with the warclaw.
Sometimes you can't place siege and get the message 'you cannot place siege here' anywhere you try to put siege down. Other players can still put siege down just fine, so it's not a siege cap issue
The second part of the bug is 'you cannot build siege weaponry' regardless of who put it down or how much supply you have. Both happen at the same time.
It's really annoying if you're commanding. Bug seems to resolve itself on player death or relog