Problems with "Export Tree"

[sblendorio]

I tried to export tree of this graphic (here exported in .vdt format):

LOGON-PAGE-RETROCAMPUS-3.vdt.zip

This is the result of Export Tree:

{"thumbnail":"data:image/png;base64,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...iaisasasasasaaiaiaiaisasasaaiaisasasaaisasasasasaaiaisasasaaiaisasasaaiaisasasaaisasasaaiaisasasasasaaiaisasasaaiaisasasaaisasasaaiaiaiebebebebebebaiaiaiaiaiaiaiaiaisasasasaaiaiaiaisasasaaiaisasasasasasasasasaaiaisasasasasasasasaaiaisasasasasasasaaiaisasasasasaaiaisasasasasasasasaaisasasaaiaiebebaiebebaiaiaiaiaiaiaiaiaiaiaiaisasaaiaiaiaiaisasaaiaiaiaiaisasasaaisasasaaiaiaiaisasasasaaiaiaiaiaiaisasasaaiaiaiaiaisasasasaaiaiaiaisasasasaaiaiaisasaaiaiaiebaiaiaiebebebaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiaiai&background=&x=0&y=1"},"children":[],"type":"content-graphics"}]}

but:

• it's not well-formed JSON
• trying to "Import Tree" with this string, produces a failure and nothing is imported

How could I export this correctly?

Thanks in advance
Francesco