As a visual learner, I normally post a screen shot or short video to illustrate my answers, hoping to help the other visual learners out there. I was out of the office last week celebrating the arrival of my newest grandchild so wasn't able to, but Mike's reply reminded me.
Here is a video, @Hendy374084080dng of my cursor hitting the blue Drop Zone.
The key to docking in the Creative Cloud applications, including InDesign, is to watch where the tip of the arrow is. You are not getting the blue vertical line when you drag the right set of panels to the left side panels because your cursor isn't going far enough to the left. It doesn't matter where the panel is, it matters where the cursor is.
Yes, you do want to watch for the blue line, but you need to get the cursor to touch what you're docking to.
Did you use the detailed instructions on how to do this posted by several other members? (Frankly, I wasn't even aware of this as I don't use apllication frame.)