I have the same problem. Just started playing yesterday and only have the base game right now and the one pack with festive things, that was listed for free. No mods either. I'm playing on PC and my sim has the freelance career.
I'm not sure about the exact moment the sketchpad broke. I used it without problems a few times and then there was only the "paint from reference" option left. That option doesn't really work either. After clicking on the camera to make the reference photo nothing happens.
I bought a new sketchpad while still keeping the old one in inventory and so far the new one still works while the old one remains broken. I finished one job with it, but didn't accept a new one so far.
There was music playing nearly the whole time and a few sims were over, so that could have been an influence.
