11mo pooing on the floor

Ours has been really happy to sit on the potty and do his business since he was able to sit but the last few days seem to be a disaster. We like to do nappy free time. He’s seeing someone on the toilet and then pooing on the floor. It’s happened twice days in a row now. I tried putting him on the potty today whilst I was on the toilet and he did a poop and then asked to get off. But then a few minutes later he pooped again on the floor. Anyone been through this or have any advice?