Our OT has noted something similar in DS5. She works with him three times a week for sensory processing issues. Once individually, once in a group of about six and once in a group with around twenty. At this point one on one he is great, in the group of six he is fine and in the large group he is iffy. The group classes are yoga/gymnastics so he is watching, listening and following instructions. In the larger class he sometimes makes the choice to watch instead of actively participating. So he isn't disruptive just making the choice to watch instead of doing the activity.
He was way more trouble a year ago. He was iffy one on one depending on if it was a new person in a new place, he was generally not good in a small group and was sometimes horrible in a large group. Group learning did not seem like an option at all. We had taken him out of PreK because he hated it and was in trouble all the time.
Now he is in a 16 kid preK/K class and is not disruptive, has friends and participates in class appropriately. There are other issues like avoiding certain types of work and suspected dyslexia we are looking into but the inability to learn in a group stuff seems to be behind us.
Whether is has been time or OT, a year has made a huge difference.
