So, you can’t use a textbox on a surface GUI? What! That should be fixed, please. Also, selection boxes disappear in front of surface guis or cut off.
If they work anything like BillboardGuis, you’ll need to parent the SurfaceGui to an individual player’s PlayerGui in order for it to work.
Textboxes on SurfaceGUIs within Workspace are not interactive by design. It’s been noted in the blog post and the documentation.
To add a note as to why this is the case: What should happen if two people are typing into the same textbox at the same time? BOOM, doesn’t quite work.
In general if you want a SurfaceGui/BillboardGui to be interactive then it has to be a local one.