App Store update and softwareupdate in terminal hang indefinitely OSX 10.13.1

The App Store shows a badge of "3" on the icon, but opening it and pressing "Updates" will result in an indefinite hang with low CPU utilization.

Tried going into the terminal and running "softwareupdate -l --verbose". I get "Finding available software" and that's it. It never returns more or accepts input again. Both using my admin account and then doing "sudo su" and running the command with sudo get the same results. 

Any ideas? Thank you!
Thanks for the help on this! I finally figured it out, well sort of. I found in the logs a recurring softwareupdate error where a mkdir command was failing. Ended up searching around on that and fixed it with:

sudo rm -rf /var/folders/zz/zy*


Appreciate the tip on the Console app. I didn't know about that and it led me to the answer!