You said it's not the cable but I personally have ran into the issue when working with a cheap cable that is designed for charging only. Prob not the solution to your problem but I figured peeps will read your post and maybe that will be the solution for a similar problem.
This is awesome work. I wish posts had a thumbnail on the left or right to give you a snippet of the topic similar to the RIF app. I'd not then it mainly feels like a lot of words and read which is not horrible but the experience is slightly lessened and cluttered.
I can think of a better way to make X go away.