PDF Embedded inside Toggle Panel issue when collapsed

[Kinga]

I want to embed PDF files inside different Toggle Panels on my website. It works fine if the panels are set not to be collapsed in their initial state. When I set the panels to be collapsed (which is what I want) the PDF files do not display; instead all I can see is a tiny rectangle (and I mean really tiny, about 1x2mm). Am I doing something wrong? Is it a bug with Ultimate Blocks? Or potentially a bug with the PDF Embedder?