Had this happen as well. What they really need is a metric ton of checkpoints. Literally save progress after every bulletin point you see during the quest is completed. Also should have saves Immediately after boss fights. Especially if there is a cutscene. Then if you disconnect at any point in the story, you are right back to the last full item you completed. Don't really care if it's more work. This has become a quality of life issue for players who just want to do the story quest ONE TIME per character. Really though, it shouldn't be hard to fix since we already have these checkpoint save. There just aren't enough of them and/or they are not often enough. When it is before a cutscene, I know there is an issue with that. I think it can't read or play the file smoothly and that causes issues.