Check your documentation for Synapse. I don't know it off the top of my head but the developer decided not to continually send all of the skeleton data all of the time to prevent the possibility of lost packets. You have to poll synapse every few seconds to continue sending its OSC data of a specific joint. I don't remember where I read this but it is definitely in the Synapse documentation, maybe on the website.

Remember that OSC messages are formatted like web addresses in a way. Like a tree system with subfolders. You have nothing between your unpackOSC object and the objects your OSC messages are supposed to manipulate. This is where you should use routeOSC or something similar in the same way you would use the vanilla PD object "route". Your bang needs to be listening to something specific (I'm assuming) and right now you're feeding it everything that is coming in on port 5001. It's difficult to troubleshoot further without knowing how your OSC messages are parsed in Processing.