Questions:
1) Had they successfully output before, using the same input item they were currently using?
2) Did all of them go missing, or just some of them? If the former, did any contents of the shed survive, and were there any changes to the shed recently?
3) No sign of them in lost and found, right?
4) When you say "after a certain amount of years", how long are we talking? How long had those Crystalariums been in operation? The more specific the better because then others can try to recreate what happened.
5) What platform are you using? Is this on PC, Mobile, Switch, something else?
6) This one is the most important - are you using any mods? If so, what mods?