Some information

Operating system: Windows
Java version: 1.8.0
Minecraft version: 1.16.2
Baritone version: v1.6.1
Forge mods (if used): torohealth, optifine, appleskin, baritone standalone

Exception, error or logs

Please find your latest.log or debug.log in this folder and attach it to the issue
No error logs

How to reproduce

1.1. Add your steps to reproduce the issue/bug experienced here.
1.2. Use #sel pos1 while standing on the block on the corner of a chunk
1.3. Move 17 blocks diagonally outwards from the middle of the chunk
1.4. Tower up by 7 blocks
1.5. Use #sel pos2 so that it creates a 17x17 selection that covers 9 chunks
1.6. Use #sel walls cobblestone
1.7. Baritone will begin building walls but will make the walls 2 blocks thick. This does not happen in any other situation.
2.1 Build a 18x18x8 block that's inside contained within one chunk but it's horizontal sides are in 6 different chunks.
2.2 Use #sel pos1 at the corner of the middle chunk (One block away from the corner of the block), on top of the block
2.3 Move to the opposite corner of the middle chunk (One block away from the corner of the block) and mine down by 8 blocks
2.4 Use #sel pos2
2.5 Use #sel fill air
2.6 Baritone will begin clearing the block, but he will mine the sides of the cube when it's not selected. Often he only does it on one side.

Modified settings

allowSprint false
allowInventory true
allowDiagonalDescend true
allowDiagonalAscend true
acceptableThrowawayItems minecraft:cobblestone,minecraft:granite,minecraft:andesite,minecraft:dirt,minecraft:sand
allowVines true
allowParkour true
allowParkourPlace true
avoidance true
mobSpawnerAvoidanceRadius 17
mobAvoidanceRadius 17

Final checklist

• I know how to properly use check boxes
• I have included the version of Minecraft I'm running, baritone's version and forge mods (if used).
• I have included logs, exceptions and / or steps to reproduce the issue.
• I have not used any OwO's or UwU's in this issue.