In Evergreen harbour, all three community lots were voted to be Maker spaces. Since last update, apart from the Sim I am playing, the only people that visit the lot are the experts in their field who...
Ideas
Try disabling the lovestruck pack if you have it. (google "disable sims4 packs" and go to James Turners site, get the required startup command, paste it in startup) and check if sims are spawning properly again.
The lovestruck EP completely destroys NPC sim spawning.
My community spaces worked perfect until the last two patches. I'm not sure which one. But they definitely worked with the lovestruck pack.