how can i fix this blockbench issue

i dont know if this is the correct place, but i might as well.

i was working on a model for archangel but i had this issue.

i cant paint the half of the pixel and now it looks very wierd (ignore that the blocks arent aligned) how can i fix or prevent this

 

You prob have two cubes in one merged, try to mark it and delete it

 

@Kiocifer help him

 

Looks like you have either a block that extends beyond 16x16 (or the program is trying to paint off the texture file), or you have a decimal-sized voxel, like 7.2 or whatever. A suitable fix would be instead of painting in the program, making a palette and applying it and then just not touching the paint portion of blockbench at all, or fixinging the size issue on the cube.