Frontpage layout in theme/clean/config.php dictates that the frontpage only has one block-region and that is side-pre (left). Yet when in frontpage with editing one and moving blocks you can drag blocks way over to the right side, well beyond the edge of the page and as far right as your screen allows.
This is wrong behaviour and needs fixing. There needs to be some kind of error handling/validation going on at this point to steer people away from trying to put blocks where they cannot go in a 2 column layout page.

I don't think this is restricted to the bootstrapbase themes, but is present in all standard themes.