I would suggest warming them up to see if that stimulates any better appetites or activity. Those guys need real heat, 90F or higher in the daytime, 60F at night is OK if they are healthy. If not, I would keep them at or near 70F at night. Note that they should have an area into which they can retreat to get cooler during the days, but I would keep most of their enclosure at 90 till you see normal activity and eating.
When I lived in CO, my Radiateds sought relief from the sun at about 95F or so, but the sulcata were active in the full sun till the temps got near 110F. When living in CT, I accidently left my full grown adult sulcata outside on a few nights when it got colder than I had expected and found them in the morning with frost on the tops of their carapaces!! Even so, the ground under their plastrons was still warm, though. As soon as the sun came up, they trudged right over to the sunniest area in my yard and sat there basking in the sun until they started to eat everything in sight as usual.
Wild caught female sulcatas I had produced fertile eggs at about 14-15" in length. Other people may have different answers to that question with their CB ones. See what is posted.