I thought I might not be seeing the black box you found on the left side of the table so I added a room model and set it to white. I do not see a black box on the left side of the table like in your screenshot.
That black box is the "surface", if you check it is the object that is above the overlays and is used to create a black frame(semi-transparent), 0.2mm high.
Now, maybe you missed something my friend..... I had given a suggestion to the 2 users who did not see the overlays (scores or balls, etc etc) and saw a black box, (that's how I understood)........even zobou had given indications for that surface which is in black color in editor (see photo)
Since I didn't see it and neither did you, and the 2 users continued to have this problem (black box), I suggested (via the photo that you rightly mentioned), I (as a test) moved the "surface" off (outside) of the table (to the left in this case) and it 'I suggested to the 2users, I also showed a photo with the editor in which I moved the "surface".....instead the problem was the overlays, which for some reason that escapes me (perhaps some setting in the video/rendering options) the 2 users did not see scores or balls etc etc, because they had the "second stage render" in selected mode.
Now if you download the table for the first time you will see that "second stage render" are disabled in all overlays,(or nothing works) look how many there are and what kind of work to put them "overlayed" so that everything works......
*send to front or send to back"
*fadeaut or fadein
*texture in "tga"
*etc etc
Now honestly I have never used "tga" for my overlays, always "bmp" or "jpeg"(with a black background), and if you insert an overlay you will see that the editor gives the "second stage render" already selected, and consequently (I (you, maybe others) has never had this problem, as I said above, overlays are a completely different story.