Ore respawns just nice outside however it has problems in mines.

However I noticed something strange in the dwemer ruin under Marchart.

I got an radiant quest to dungeon so I visiting it a second time more than 10 days later, clutter and enemies had respawned.

The cell with the spiders before the city itself has iron and cordium ore who looked normal but you could not activate the ore then entering the cell, however then exiting after getting the item in the city the ore worked again, same was true for moonstone ore at the exit of the command house.

Downside is that most mines don't have multiple cells.

Had the same thing happen to me with the Stalhrim Source. Had to reload a previous save and I worked just fine.

Checked in the uesp, looks like entering the mine, exiting and enter again solves this but has not tested it yet.

Yes, you need to exit and re-enter. That will fix ore veins in mines.

I used to have this issue as well until USKP presumably fixed it.