I am having the exact same problem............lvl 21 right before fighting act 1 boss , jumped into a friends game to grab a item who has cleared all of act 2 now I only am able to play from his save point not mine.

Same issue here. I cannot go back to my Act story after grouping with a friend who was ahead of me in the story. Now I am stuck not able to fight anything because everything is twice my level. Need to be able to select Act to play regardless of level.

Im having the same issue, help please, i dont want the story spoiled before i get to it

Same for me i need some help

still no update?

+1 to this.
Can no longer progress down MY path.

Same here, please fix this! ASAP

Same, Basically bricked my friends character. His menu still shows his accurate progress in the act, but he can't use his waypoints now. This is a big issue.

Same problem......

This has been my case for over a week, so frustrating! I can't leave the group. When i join a game it thinks i'm still in a group. Tried rejoining with friend and clicking leave group but whenever it connects to server again at the very end it says "getting group" every single time! I'm no longer in the friggin group!!! Grrrrrr

Same problem here.
I was in the middle of the Act I at lv13, then a friend (lv63, finished Act III) joined my session, we played a while together.
Then we switched, he opened a session and we played a while. Now if I login, my campain progess is gone, I'm after Act III, still with my low level.

Has anyone found a way to "go back"? I'd hate to have to replay from the beginning...

Match Making just did this to me; I had JUST got to 'Daybreaker's Valley' in act two last night. Set the game to public mode and it matched me with someone who was at the end of act two! So i left that group to play solo again, now I'm stuck with that other player's progress with no way to get back to my own character's story progression. It's a pretty big issue. PLEASE fix this!

Bump bump bump this thread. Thanks.

Same issue here.

I'm a lvl 16 trapped in late Act II. There is no way to go back to my own saved game.

i have same problem, pls FIX asap....

[EDIT] I gave it a try and can confirm that after a long game session in my lvl 10+ friend in Chapters I & II I was able to get back to my lvl 30+ Chapter III with no trouble.
[/EDIT]

Hi!
Can someone please confirm if it is safe for a lvl 30+ character at Chapter III to join a lvl 10+ friend in Chapter I and then safely keep on playing in Chapter III afterwards?

Yes same, my friend came to help me on a boss and went from chapter 2 to chapter 3, and now they cant go back to progress on their campaing on their own. So they lost like 30% of campaing content because of they helped me :/

Had this issue happen twice to me now. Just about to end the first Act and teamed up with a friend who was almost finished with Act Two. They became the group leader because my game froze up. Didn't think anything about it until they left the party and now I'm stuck at their progression level and I haven't even started the second act yet. Has anyone found a way to solve this yet other than starting completely over with another character?