Ideas
Is the maker space the only community lot you have issues with or do you have also no Sims on other lots ?
Okay did some more testing.
First I changed one of my three Maker lots to a Community garden. Nobody but my active Sim went into the built area. (Sprucewood). Usually at least Agatha and Agnes turn up immediately regardless of time of day and throw plants onto empty garden beds and sometimes plant them.
Then I started a new game with one new character. No mods. No cheats. I built up community points in the usual way by introducing Sims to other people.
Moved my Sim into Canal Corner. Voted on Sprucewood Square to be Marketplace this time, using the default design. Once it changed, random townies turned up and started chatting to each other eg Nancy Landgraab, but no one with Vendor above their name (as there usually is) so nothing on tables. The food van remained closed.
I then played the Greenburgs and Bess and Jules to get enough community points to turn Port Promise into a Maker space and Green Initiatives. Again the only people that turned up were the Master Crafters, Recycling Gurus and my Sim. Tina Tinker turned up immediately and started making candles or used Fabricator. Lily Feng was a Master Crafter and there were about three others, all ready to Mentor. But no one to mentor. I suppose you could have your Sim invite a stack of random Sims or friends, but you didn't need to in the past.
The Harris family looked after Grims Quarry which was turned into a Community Garden. Result was the same as mentioned above. No one turned up at all.
This totally breaks the Community Lots. Before, it was like the gyms or library. Random townies come and build whatever skill they use at the same time as your Sim.
San Myoshuno Meadows is empty like that. Your active Sim and guests are the only ones there (though you see a Mixologist leaving sometimes) This is good for private parties and dates, and is somewhat realistic as a Venue for weddings etc. But Community Lots are for community. Random people coming and going, even your non active Played household members would randomly turn up and use woodworking table etc.
The Casbah Gallery still works in that people use the facilities. But strictly speaking it's not a Community Lot.
Now :(