If you accept credit from someone else’s story, you will advance through their story until the end of the chapter. This isn’t a bug, it’s intended so you can continue to quest with your friends. It does not actually change what order you are in, once you complete that chapter, and as long as you don’t accept credit again, you’ll return to your story track.
Okay, I’ve done a lot of reading on this trying to figure out what is going on and I’m pretty sure all this “It is isn’t a bug, you accepted it when you hit accept” is just… kind of player-blaming for stitched in poor design. As far as I can tell it’s them covering for an unintended effect of their game design mistake.
Accepting someone else’s progress does accept their decisions when you play a concurrent chapter together (and that’s fine!), but no decisions are made in “Setting the Stage”. The player character hardly has a role in it at all. You just watch a scene. The decision of what order to join had already been made in previous chapters. There are no decisions the other person made that you have to decide whether you agree with them or not. From a gameplay perspective, it makes sense for anyone of any order to be able to play it together and accept progress, because it would be tedious to play it again. But from a storytelling perspective it doesn’t make any sense for the players “actions” there to change their order for a chapter (erasing their meeting with their mentor, their introduction, and so much else), when that decision was already set in stone beforehand.
It looks like, from reading, that Setting the Stage was added into the game post-release. I don’t think this is an “intended feature so you can play together”. Because you can always just “join instance” with party members on anyone’s story no matter what order they’re in or level they’re at. You don’t need to be on the same story track. The three of us played levels 10, 20, and 30 together all choosing different things every time and having different storylines (from our dreams to our battle plans) didn’t stop us from playing together.
As much as devs might be trying to say this is a feature, it’s not. It’s a bug. They added this story piece in later and it created an unintended consequence of erasing player’s decisions and progress for their stories. And it looks like there might be no way to get out of it without missing my character’s actual level 40 Order story, which is genuinely upsetting.
Either “Setting the Stage” could be changed into a non-concurrent story chapter, so if you aren’t in the order of the character playing you can’t accept progress (e.g., “Setting the Stage: Vigil”, “Setting the Stage: Priory”, “Setting the Stage: Whispers”), because a little bit of having to replay is worth not getting stuck in a storyline you didn’t choose (it sounds like this is how it used to be, before the chapter was added. Each order had their own version of this instance at the beginning of their first Orders chapter and instead they combined it – with the recent story reversions/fixes, given that this is a known problem, this could have been reverted as well). Or you put in a fix where accepting progress progresses you along your order, no matter the order of the “active” player.
I imagine the first (just splitting it so this can’t happen) would be easier to implement than the second (knowing what little I do about programming – creating an exception to the “accept progress” rules is probably harder than just copypasting a chapter into three versions of itself). But I feel like trying to say “it’s not a bug!” is disingenuous. Being able to accept another character’s progress when you’re on concurrent stories (and de facto accepting their decisions through that) is a feature; this unintended result of that feature is absolutely a bug.
At the very least in the meantime you could put a note on the acceptance for this chapter that says “If you accept this progress you will be progressed into the [Instance Owner’s Order]‘s Story. If this is not your order, you will not be able to play your order’s story for the rest of this chapter in your personal story.”