Vanishing Parts Julian Quest Glitch
Category: Episode 2 Quest Glitch
Class: Authentic Glitch
Platform(s) Affected: Windows (as far as I know, other platforms could be affected)
Current Status: 
Unresolved as of 12/24/2021
Glitch Occurrence/Specification: Infrequent. Occurs 50% of the time or less.
Glitch Reporter: @Sierepica_Fuzzywalker
Related Glitches: None for certain. Could be related to other Episode 2 glitches.
Details:
Affected Quest: "Julian Ships Out".
1. Player collects all three of Julian's airship parts (wings, seat, and wheel).
2. Player places the parts on Julian's airship frame in the wrong order. In my case, I placed the seat on the frame, then the wheel, and finally the wings.
3. Julian smashes the parts because they are in the wrong order and they appear to fall off the mountain.
4. Player cannot find the parts to Julian's airship to place on the frame. Returning to the places where the player originally found the parts has no effect and does not restore the parts to the player's inventory. This prevents the player from continuing with the Episode 2 Storyline.
Side Effects/Similar Issues: After relogging into the game, returning to the places where the player found Julian's airship parts causes the player to earn a cog or pipe and Aether. This causes the quest icon for the "Julian Ships Out" quest to glow yellow and the word NEW to appear on the quest, as if it has been updated, but opening the quest reveals it to be in the same stuck position.
Statistical Polls: Vanishing Julian Parts Glitch Poll
Screenshots/Video Evidence:
If Julian is in this position, he should be surrounded by the parts he just knocked off the airship frame, as per this post:
Julian also says that the parts should be scattered over the mountain after the parts are gone.
This is how the quest dialog appears after the glitch is triggered:
