Hmmm, I have a 22 month old and did not have that problem with him, but I did watch a little boy that was a very picky eater and had to drink health shakes with all his food pureed, he too was just alittle underweight, but very healthy. I thought it was strange, but that was just him. Babies are all different, I would not worry too much if he is eating the pureed food good. Dont force it on him, but just keep trying. Try all different kinds of small foods, like cheeze, blueberries, small snaks, etc. Just keep trying and dont make it an issue. Your little one will grow out of the "not eating solid foods" just keep woking on it and make sure to model eating in front of him/her. My son was a great eater until about 21 months, then all the sudden he became picky and more demanding - we work with him, but we also make sure that he gets all his food groups. For example, if he does not want the yogurt, we make sure he gets his milk and cheese. If he does not eat peas, we try another green veggie, and we never have problems with him eating his fruit. Just keep trying and dont give up and dont get discouraged!
Hang in there, your little one will be eating soon enough.