So a bit of an update regarding what might be happening. I can confirm the shutter release did in fact work this time. The problem is the camera only actuates the shutter when it is disconnected from the pi. As long as the camera is tethered it wont do bulb exposures using the shutter release. I checked this by starting a series of exposures using the capture module, and then when they started failing I would disconnect the camera by pulling out the usb cable. The camera then would do bulb exposures as normal, but obviously wouldn't transfer the files to the pi. I can however verify that bulb exposures while tethered are possible, as I have taken 320s bulb exposures with the capture module in the past. There seems to be something going on regarding the tethering as well as the shutter release. I can't figure out exactly what the cause for the inconsistency is, but will continue to provide information as I come upon in. One thing that I will test is seeing if different batteries affect this behavior. I was able to get imaging working as normal earlier today, but had to switch batteries right after this as it was running low. Upon restarting the camera and kstars I couldn't get the exposures to work again. No amount of pi, kstars, or camera restarts fixed this. It is unclear whether it is due to the battery itself, or perhaps just some other software related issue.