I rebuilt the guildhall close to the mint and it started allowing Dwarves to join up.
However I have a new problem. I disallowed all of my dwarves save my 4 metalworking dwarves, and set up a "Join Smith's Guild" action.
The dwarves will go, pick up the coins, and go do the action. It will display the message "A dwarf has joined a guild". But they don't actually join.
After my 5th try, a dwarf turned into an apprentice dwarf and joined for real. Nobody else has since.
None of the 4 were part of a guild to begin with.
Is there a chance, based on some stat, that the "join guild" action won't work?
You have to remember that a lot of things in Masterwork are actually scripts running through DFhack. You need to do one dwarf at a time. Only one dwarf allowed to "use" the guild and wait for him to become a "dwarf joining a guild" AND turn back into a normal dwarf in a guild. That's the safest way to do it. It sounds like you let four dwarves have access and queued up four "join guild" jobs. Every dwarf that went overwrote the previous reaction just costing you money. Never use repeat on these reactions or queue up jobs. I'm guessing your fifth attempt was with one dwarf and thats why it worked. You just have to be patient with guilds. It's not meant to be something where you assign all 200 dwarfs to guilds eventually. It simulates sending a dwarf to specialty training in a skill for several months to become better. Not every dwarf can go to college.
Now I'm not sure if you can have multiple guild halls and let dwarves use each one to be faster or not. When the reaction takes place you'll notice a burst cloud of dust. The combat log will sometimes say "caught in a searing cloud of knowledge" haha. So if you have a dwarf on the guild hall already running the reaction, then another dwarf uses the guildhall causing another burst of knowledge it will screw things up. It could be possible to have multiple guild halls so that dwarves don't get caught up in multiple bursts of knowledge. Maybe experiment with that.
Also remember that the reaction does actually randomly change your dwarf. Injured dwarfs will magically grow back limbs. It's a limitation of DFhack scripts. This also means that their skills will be randomized. So if you have a high master smith and have him join the smiths guild he might randomly drop down to "dabbling" in that skill. In that case it would be best just to let one be out of the guild and continue training. I usually use guilds on lower skilled workers so they will level up faster to catch up with my original legendary 7. You could also rush to get it early on so you don't have to worry too much about randomization.
I see also you're minting gold coins. This is one good way to do it. You can also use the trading system. If you get trade licenses you can build the trader workshops. At these you can sell things for coins. I like to sell feather wood logs in good embarks for silver coins. You can then use the tavern workshop to convert lower value copper and silver coins into gold coins.
So overall just don't use repeat for reactions like the guildhall. Repeat works for things like the tavern because the script is run instantly. But guilds are a long script with a timer before the reaction is done and DFhack just does not like this happening. The same applies for the military garrison and the monastery. Your patience will be rewarded with powerful legion soldiers, grand master smiths, and unbelievably powerful wizards if you take your time and explore each path. Masterwork has so much content you can play for hundreds of hours only to find you never scratched the surface of an entire branch of the mod.