Yeah, they don't mine

I've had this. A few things to look out for (I'm sure you already have but someone else reading might find it useful) -

-Check to see if your storage area(s) are full. They seem to do nothing if that happens.

-Check to see if they can access all areas. It could be that you've build a tile somewhere instead of a pillar. They cannot walk through tiles. I've inadvertently done this many times and took way too long to realise, especially when building my concrete areas. There may also be a single block somewhere that means they can't get to further resources. Check all your ladders and routes. Kind of like doing a 'find you way out of the maze thing' Yes I've done this too.

-If you haven't yet, try assigning each Golem priorities options, especially those that suit their traits if possible. The button for that in the top right section of the screen.

-Regarding the slow ammo loading - Make sure you have lights around the base, especially outside of the rooms, this helps speed them up, and will also restore a little HP when they are in 'Warm light'. Assigning Golems to 'Transport' in the priorities should also help with this.

I still haven't beat this game, so these are just a few things I've discovered over many many frustrating but fun game play hours and new games.

Hello, thank you for trying the demo.
I apologize for the trouble. The tips from MessyBoots above are great.
We realize now the AI of the Golems in the demo was not great, it should be improved in the Early Access version, and something we will continuously be working on.

sometimes golems get confused if they are trying to transport an inaccessible item, especially if it is a special item (from a shiny tile.) in that case you need to make sure that golems can reach every item on teh map by basically forbidding one golem to transport and force him to make it accessible.