When I approach some ore and press e I start to mine but don't actually get anything. Also, he keeps mining forever. Pressing e again will stop my character and I have to mine the ore manually. Not a game breaking glitch but an odd one - anyone else getting this?

Do not mine manually the mine might not respawn at a later date.

If pressing e does not mine. likely you have the animation glitch. Usually sitting down, activating an anvil, armor bench or something that puts you into third person. possibly trying to toggle between crouch a few times to make sure you are standing. I believe this happens if you are crouching(sneaking) and activating the mining animation and since the animation is based on standing it might just do the animation and not the actual mining.

to clarify - he whacks the vein with his pickaxe but receives no ore and the vein is still minable after. Does this count as an animation glitch - I will try what you said though.

If pressing e and he/she starts to mine with the pickax in third person view and nothing happens is most likely the animation glitch that goes on and on. Sometimes canceling out and then trying it again will work.

Thanks I'll try that too