you not only cannot have space between the top of the powder column and the base of the bullet, but that black burns more efficiently if it's somewhat compressed. So the procedure for long-range shooters(in particular) is to measure the powder charge, drop it into the case using a drop tube, then to use a compression die* to compress it to whatever degree you're using, then seat the bullet.
That round with the dud primer? Using that bullet set at that depth, takes a little over 2/10" compression of the powder. Pulled the bullet and the over-powder wad, and barely a granule of powder came out; the charge might as well have been a single pellet. Had to use a drill bit to dig it all out. I'd say the process did a very good job of compression.
The primer had a very nice dent, can't really tell if the priming compound was missed on this one or somehow contaminated.
*Basically a expander die with the expander plug replaced with one that's solid and just fits into the case mouth; allows you to set the depth and compress the powder to a very consistent amount.