Dude I had the exact same problem. Solution: You have to research the thing with the most time before you can actually build. I researched organs and brain implants before it and I had no new workbench.

I hope this helps ^^

Yeah, I just did the same. It seems weird that you can research so many things before actually getting the bench where youu can use them. Maybe make it so that the bench unlocks with the advanced component research, and make that required for synthetic organs and such.