Some of the existing slices have problems meshing well with other certain slices. Below is some puzzling I've done to figure out why certain slices work sometimes but mess up other times, and my suggestions as to how to avoid making vertical slices which will stuck some buildings or caves.
In the case of a slice that looks like this
FFFF@,,,F
F,,,,,,,F
F,,,,,,,F
FFFF,,,,F
F@,,,,,,F
This slice could correctly fit with a slice that looked like this
F@,,,,,,F
F,,,,,,,F
F,,FFF,,F
F,,FFF,,F
F,,,,,,,F
F@,,,,,,F
To look like this (added second slice on the top and bottom of the first slice):
F@,,,,,,F
F,,,,,,,F
F,,FFF,,F
F,,FFF,,F
F,,,,,,,F
F@,,,,,,F
FFFF@,,,FFFF
F,,,,,,,F
F,,,,,,,F
FFFF,,,,F
F@,,,,,,F
F@,,,,,,F
F,,,,,,,F
F,,FFF,,F
F,,FFF,,F
F,,,,,,,F
F@,,,,,,F
But it would not work if the second slice looked like this:
F@,,F
F,,,F
F,F,F
F,,,F
@,,,F
Which would produce the following:
F@,,F
F,,,F
F,F,F
F,,,F
@,,,F
FFFF@,,,F
F,,,,,,,F
F,,,,,,,F
FFFF,,,,F
F@,,,,,,F <----- here is a blocked passageway
F@,,FFFFF
F,,,F
F,F,F
F,,,F
@,,,F
As you can see, there is a 1-block high passage on two otherwise functional slices. To avoid this, ensure that the slice guide marker has 1 block clearance of open terrain below or above in all vertical segments.
In the above example, changing the first slice to this will fix the issue:
FFFF@,,,F
F,,,,,,,F
F,,,,,,,F
FFFF,,,,F
F,,,,,,,F <---- added this extra space, slice guide isn't vertically crowded
F@,,,,,,F