Office Viewer plugin does not work with spaces in the attachments filename

After upgrading to v3.5 we noticed that newly uploaded PPT files did not show using the office viewer plugin. The preview stays black and keeps loading. On the server side I could see that the slide images had been created.
We figured out that the uploaded files have spaces in the filename. I believe the previous version (v3.1.1 for us) automatically removed spaces from uploaded file names. We were able to work around this issue be re-uploading the files without spaces in the filename and then the plugin worked again.