I'm having a very buggy problem happen with a graphics layer I created from the "Convert labels to graphics" tool. I used that tool initially and then added some other text and arrow graphics to the layer manually.
Here is a link to a screen capture video of what is happening: https://www.screencast.com/t/Mcg2WtZhE
Basically, there are arrows showing up in places they should not, and they move around on their own when I change extents or interact with other graphics. I can not select the arrows themselves, but noticed that if I select a large area, some additional "ghost" objects get selected. But the problem is that I can't tell where the "ghost" objects actually are because they are invisible! It is also plotting to PDF this way.
I am on Pro 3.1.2, and I cleared my display cache to see if that would help, it did not. Anyone else encounter this or have a solution?
Sorry, I haven't watched the video (it'll get blocked) but it sounds the graphic is "existing" outside of the graphic's box. Perhaps you can try selecting the graphic/phantom box, choose properties, choose the placement icon and see if you can adjust the positioning option with the position boxes (included in the pic below) to see if that helps (this can also be accomplished via the ribbon's "Text" tab when the graphic/phantom box is selected). Just an idea but I hope it helps.
I've had converted graphics "unexplainably" get "corrupted" with some layouts in a map-series in the past. I ended up deleting the graphics and starting over.
I had the same thing the other day and did some deep to find out the reason.... Problem it looked like you might have accidently hit the wrong Target Layer. So, if you select one, copy and paste and make sure you change the Target layer to correct it ? Have you tried that method ?