I have dealt with line problems in repeat patterns before. All the normal fixes will not work. The first photo is the repeat printed on fabric. The second is what shows up in extreme zoom in Ilustrator. Anti aliased artwork in turned off, artboard is fit to artwork, etc. HELP! What is the issue? It's not the normal clean line across repeat pattern. If you look at the second photo, the extreme zoom shows a jagged breaking up of the color.
If the line still shows when antialiasing/smoothing is turned off in the preferences, then the pattern is not exact. Could you check the aligning of points? Or if there are handles going out weird?
The pattern was made using the pattern make window in Illustrator so it should be exact. What do you mean by "handles going out weird?"
When handles are in a place where they shouldn't be.
Using the pattern editing mode is not a guarantee that nothing can go wrong. It depends on how you use it. When using the pattern editing mode, it's better to abandon the old way of making patterns. If you continueusing some of the old pattern workflows, then there are possibilities for errors.
Without seeing the actual file, it's impossible to help you much.
Is it possible to send you the file?
You could upload it to your Creative Cloud files, make it downloadable and send me the link via private message.
Thank you! I have private messaged you the link.