This sounds like the tube is getting caught/pinched between the tire bead and the bead seat at the stem. The rubber around the base of the stem is thicker than the rest of the tube, and tends to be the area where it will push its way under the bead.
This happens with certain tire and wheel combinations, especially if you tighten the valve nut before inflating.
1. I would go with cloth tape that covers completely edge to edge.
2. Put the knurled nut or a washer on the inside, meaning before you poke the stem through the rim hole when installing.
3. As you are inflating, keep pushing on the stem and checking that it's free to move.
4. If you use another nut on the outside, just barely snug it down and only after you reach full inflation.