DarthParametric

Interpreting comments from CDPR's post-delay teleconference (albeit via someone else's translation from Polish to English), it sounds like it's probably the Xbone and PS4 releases causing them grief (presumably the Xbone S particularly).

I didn't think a game could get delayed after it "went gold". Can't say I was expecting this one.

Well "gold" is just the locked content master sent off for physical manufacturing. These days it's typical to not worry so much since you can just fix/add things with a day one patch. Although there are rumours circulating that this particular instance is more critical and there is an issue requiring recalling the PS4 version altogether, since it may cause hardware issues (possibly bricking the console altogether). It could just be the usual internet BS though, impossible to say at this point.

But that aside, such a delay right before release is very unusual, mostly because of marketing. That is probably going to cost them 10s of millions of dollars, at the very least.