Recently i’ve been noticing a trend in WvW and im not sure how exactly to reproduce it however it’s happened twice on my Elementalist.
Cannons, specifically those in fortified towers/keeps will display an error message if you attempt to use them after jumping to their location. “Cannot use siege while holding a bundle” or something to that effect. This leads to you being unable to get off the siege as well as you get the following message “Cannot drop bundle in air”.
The only work around for this is to waypoint / leave the map or be killed on said emplacement.