As the summary says, whenever I try to use the fill command, it leaves large gaps (see attached; note that in the attachment I've used the command at least 3 times so the gap is even larger).

Steps:

1. Use the fill command.

e.g.

/fill 0 4 0 500 13 0 quartz_block

Update: I've added an additional screenshot. This is just ridiculous.

Relevant commands for the 2nd screenshot:

/fill 1 4 -1 300 4 -100 smooth_stone

/fill 1 4 -200 300 4 -100 smooth_stone

/fill 1 4 -200 300 4 -300 smooth_stone

/fill 1 4 -400 300 4 -300 smooth_stone

/fill 1 4 -400 300 4 -500 smooth_stone

/fill 301 4 0 301 10 -501 stonebrick

/fill 0 4 0 301 10 0 stonebrick

/fill 301 11 0 301 11 -501 quartz_block

/fill 0 11 0 301 11 0 quartz_block