Very strange??? Is the bolt picking up the round out of the magazine, or is it just sliding over it? Sliding over it sounds like a follower, spring or internal magazine problem. Picking up the round and jamming it into the breach face, not the chamber, is another.
Addendum: Another thought, after a bout with CRS.
It’s been a while since I took a 700 apart and don’t have one handy to look at but I think it has an internal metal box magazine that the follower and spring fit in. Make sure this isn’t bent, put in upside down, or backwards and seated in the proper place. Somewhere in the back of my memory I recall someone else having a similar problem and this was it.