Following up on an old archived reddit post here:
https://www.reddit.com/r/prey/comments/8uzzy1/no_plans_to_fabricate_error/
There's a fairly common bug where the fabricator will display a "No Plans To Fabricate" error. The reddit post suggested a few solutions around clearing the tray with frags and the likes but those didn't work for me.
After a lot of trial and error, I found a completely different solution that suggests an entirely different bug: In Data -> Plans, click to read about Morgan's Arming Key. To be safe, do so for all the plans.
If I had to guess, two possible causes come to mind:
The bug is triggered when you hold off on fabricating Morgan's key (since it takes space) and instead go off to do explorations and side/major quests. For me (and others as the old posts suggest) it seemed to coincide with the Turret fabrication fight in the Cargo Bay shortly before Reboot.
A bad quest item trigger for Turrets: The fabricator probably has at least two item numbers for Turrets (a generic one and one for the quest line). So, when you finish the quest, if the last thing you toggled the selection on was the old Turret, since it's now disabled, it will create a "no plans" bug. And when you go into Data -> Plans and toggle to a different plan, it will reset the toggle.
P.s I tried posting this on reddit but the original thread is archived while doing a new post didn't work for some reason.
https://www.reddit.com/r/prey/comments/xum2qc/re_no_plans_to_fabricate_error/