Since we are all guessing I am guessing it is a combination of 2 and 3. Fill the race with bearings and remove one, they should not be crowding together so that some are being pushed up. Too-tight adjustment will cause a gritty feel.
If the cone and locknut are not locked together sufficiently tightly the cone can tighten itself during riding. You can use the locking process to fine-tune the bearing adjustment, turning the locknut against the cone tightens the adjustment, turning the cone against the locknut loosens it. Tightening a quick release will compress the axle slightly, tightening the adjustment, so this must be allowed for. The use of an axle vise is very helpful, here is a good one:
https://www.steintool.com/portfolio-...ub-axle-vises/
Here are a couple of articles which may be helpful.
https://www.sheldonbrown.com/tooltips/hubs.html
https://www.parktool.com/blog/repair...and-adjustment