If an item isn’t stockpiled, it doesn’t count towards the “maintain X of Y” tasks for workstations.
Steps to reproduce:
Construct something without a stockpile to send it to, or something that can’t be stockpiled like fences (or flour in Why So Blue?).
Items constructed by the workstation should count towards the maintain counter.
A worker will continue producing that item indefinitely, flooding their surroundings with whatever it is that’s not being stockpiled (like fences) and creating all sorts of graphical glitches as everything fights for z-levels.
Versions and Mods:
1687 for fences, Why so Blue? v8a for flour.
Windows 10 Technical Preview, AMD Phenom II x6 1075T, Nvidia Geforce GTX 770 (2 gigs VRAM), 6 gigs RAM.