This is preeety weird - given that it has an entity handle id I assume that it is somewhere in the file. Just hidden or not correctly stored. I think @andreaatsafe​ should pass it along to the dev team to see what's going on.

I also uploaded it to Autodesk free online viewer and couldn't see the little box.

I've seen stuff like this before where there are boarders with different scales that do not behave as expected outside of autocad. There are also a number of boxed on the 0 layer which could be related somehow.

Thank you for the input. It would be great if an expert can dig deeper on this and find out what the issue is

Do you know which tool initially created the data? was it authored in AutoCAD?

This is how my agency received the file from the source. No idea about the licensing issues in the source.

This is a very complicated issue in AutoCAD!

For example, in the screenshot below, if the content of the dwg file is selected with the (ctrl + A) then it shows objects that are not visible before the selection (knowing that all layers are turned in both cases)

Not sure how FME could catch such errors and fix them

The dwg file is attached