Plug spinning in hole!

[Nanako]

Do you know what the construction of the wall is?

My guess, and it is just a wild guess, is that it's (from the wall surface inwards) tile, plasterboard, stud frame with void in between, brick/stone.

To clear up the size confusion, the suggestion is that you've drilled the hole too big, because you're using rawlplugs that are too big for the job. So the suggestion is that the hole is therefore improperly sized for the job.
Anyway - that's water under the bridge - more crucially - what do you know about the wall?

mystery deepens, i have just drilled holes for my second shelf, about a foot above this one, and i hit masonry on both of them!

My best guess is that there is masonry there all along, but at the first spot i drilled, it was crumbly and damp, this is an occasional problem around here

 

[Alec_t]

Maybe the first hole just happened to go between two bricks which weren't properly bonded by mortar?

 

[foxhole]

Probably studwork so you are drilling into void, 6mm would be more than enough for tiny rack .
Suction or self adhesive rack would have been easier , no drilling required .I used these in my shower wall panels to avoid drilling .

 

[Alec_t]

I didn't have much luck with suction fittings like that. The rack fell off after a couple of weeks. Close inspection showed slight undulations in the tile surfaces, which presumably allowed air to leak very gradually into the fittings.

 

[foxhole]

I didn't have much luck with suction fittings like that. The rack fell off after a couple of weeks. Close inspection showed slight undulations in the tile surfaces, which presumably allowed air to leak very gradually into the fittings.

Mine are a combination , vacuum with adhesive .

 

[Nanako]

Probably studwork so you are drilling into void, 6mm would be more than enough for tiny rack .
Suction or self adhesive rack would have been easier , no drilling required .I used these in my shower wall panels to avoid drilling .

these shelves were self adhesive, they came with little sticky pads, seemed low effort so i tried them out
they fell off the wall after two days. Garbage method of mounting

now theyre screwed in and that will not happen again

 

[foxhole]

these shelves were self adhesive, they came with little sticky pads, seemed low effort so i tried them out
they fell off the wall after two days. Garbage method of mounting

now theyre screwed in and that will not happen again

Yes the sticky pads alone are cack .