Projection Building Attachement Points Not Working

There are a few critical bugs I am having with the projection building system that are likely all related/the same so I will list them here:

1. If you try to place a block onto a projected block and it is adjacent to a non-projected block, you can not place it. However, if you try to place it onto the non-projected block, it then places fine - but only if there is an attachment point to the non-projected block - if it's to the projected block, it still won't place. See attached images.

2. Undo-redo will often ignore my most recently placed blocks and undo-redo the ones before that instead. Example: I place block "A", block "B", and block "C". I press ctrl-z, and block "B" is removed, not block "C". I press it again, and block "A" is removed. Redoing brings back block "A". Block "C" is completely ignored. I think there is a connection between this and the first bug - if I place the block in a position between a projected block and a non-projected block, the block seems to be ignored by the undo system.

3. Symmetry will sometimes ignore certain blocks I place. I have not figured out what causes this or how to reproduce it yet, but I assume it is also linked to this.

Let me know if you need any other info to fix this: but it seems to be extremely easily reproduced so I suspect you can just test yourself to figure it out.