Hi there! I complete the level 2-1 in 3 seconds and achievement doesn't work for me

Hello! I tried the demo and i've completed the available puzzles. Overall is very good, but I found two things I think may need to be fixed. The first is that the "undo"? button does nothing. You hear the SFX but it does not reset o remove any pieces. The other is that the C piece when is placed sometimes is a little bit offset from the tiles, doesn't affect to the placement for the solution, but it is a bit ugly. https://i.imgur.com/cvIGX87.png I had fun! Go...

I complete the fourth chapter, but the first level of fifth chapter is bugged, remains in blank window. Also all achievements for complete all levels are broken The game is really cute, thanks