EC paused again

I was trying to be consistent and put my son on the potty after each meal for about 10 min. He used to poo right after each meal (3 poos a day). But since I began putting him on the potty, his poo schedule became erratic. He just wouldn't poo or pee in the potty. He would hold it in until he is off the potty. Now his poo schedule is a lot more unpredictable. I'm not sure what I should do other than putting a pause on the EC training - AGAIN! Arghhhhhh! Does anyone have any suggestions?