I was having the same problem. For the last few days I couldn't get higher than 95% and I did everything I could. Then this morning while I was in the middle of cleaning up/cracking rocks/cutting grass, I see a new townsperson with an exclamation point over his head. I got a new resident and was never even notified, lol. I just happened to see someone new running around. I was at 93% when I opened the game this morning, so it happened while I was playing, but the game never stopped to tell me he moved in.