I am actually having the same issue. Nearest is never on for me, it's used rarely as an override, as with perpendicular as I have had random snap issues with it in the past. I am certain that my lines are off, it becomes obvious in my dimensioning. Although lines are set out using offset, the dimensional stack error will add up to be a millimeter off over the course of a few clicks. A millimeter may not seem like much from an architectural standpoint, but consider the same stack error over the span of a 150' curtain wall and you might appear 3/4" short over the complete run, and this becomes a major concern during the creation of fabrication drawings. I've been using autocad since release 14 and have not had this issue until using 2012.
I have ran into this bug with drawings sent to me using the e-transmit feature in Autocad. I think it happens when a drawing is saved back to an earlier version. Usally the offset snap point happens with ojects in a block.
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