Was testing this with a friend on an Essential multiplayer server, and when the slabs are placed, it is not synchronized between the two of us which results in things looking different and collision issues. When mine was flush against a wall, his was rotated to the right side of the block. This was a Bewitchment modded block in particular but since this is supposed to work with all slab variants I don't imagine that would be the reasoning. This happens no matter which one of us placed the block, either him (the host), or me.
Was testing this with a friend on an Essential multiplayer server, and when the slabs are placed, it is not synchronized between the two of us which results in things looking different and collision issues. When mine was flush against a wall, his was rotated to the right side of the block. This was a Bewitchment modded block in particular but since this is supposed to work with all slab variants I don't imagine that would be the reasoning. This happens no matter which one of us placed the block, either him (the host), or me.