When I was completing the level 30 I thought I should do the oops! Achievement first and I did, but..

I had the same problem, I replayed the level 30 after failing it and didn't get the First Try achievement. I desided to finish the whole game first (51 levels), then try lvl 30 again, and it worked, I got the achievement. I was worried that (in case it doesn't work) I'd have to reinstall the app and replay the first 30 levels. Luckily it wasn't necessary