Working on a project with someone, you know your character has all the necessary tools and, because you started a tick earlier than them, you also know how much progress your character makes each tick. You go to sleep thinking the project will be finished in 6 more ticks, but when you check in again, you see a tick go by and the progress has only gone up by the amount your character is doing...and your partner hasn't got the usual 3% project tick tiredness, so, obviously, you assume out of the three tools needed, that it can't be either of the really basic ones that they're missing...and so ask if anyone has a spare of the other to pass them. Someone does, you think problem is solved. However...next tick passes and your character is
still the only one making progress on the project!! Whaaaa...!
Summed up annoying part: not being able to tell which tool someone helping you on a project is lacking, because they're all non-visible tools, even though they technically
would be visible when in use...