It is very annoying to have written a tutorial with images, only to lose it when uploading. This has happened to me several times, and I have now discovered the reason.
You can't use TIFF files when uploading a tutorial!
The files won't appear and your text will be deleted! And you will feel like a fool :-(
I suggest, that GrabCAD revise the code, so that the text remains even though images disappear, if possible. This would immediately indicate to the uploader, that the image format is not accepted.
FYI: TIFF is a great format because it is lossless, supports compression and 32 bit colour (CMYK), alpha-channels, etc. Very much used in graphic design.
Thanks for making us aware of this issue, Steen. We will to get this resolved in the near future! Sorry for any inconvenience.