Here's exactly what I did, I grabbed a barrel and went into the mine are, tried to place near the mine entrance, behind some bushes, could not place, went to the north side of the mine in the rocks, clicked to place the barrel and was knocked out. When I came to I moved over by the excavator and tried again, was knocked out as soon as I hit the place button again, moved a few more feet to the south side of the conveyor belt and it happened again.

During the first barrel drop I was bleeding, maybe that contributed to being knocked out. I noticed it and fixed it when I came to, when I tried to place the barrel subsequently I was knocked out again, each time. Low blood maybe??

I have not tried to place a barrel anywhere else in game.