[PeterT]

There are two distinct formats in use. I think (but am not certain) that the iPad and other platforms make use of the so-called kePub format. This you can get onto your Kobo IF you use the Kobo Desktop.

The ADE version is in what is called the ePub format.

For the heck of it, try launching the Kobo Desktop and doing an Update library there. That should bring the KePub format down to your PC and make it available in Kobo Desktop (but NOT in ADE). See if the diagrams are there.

If they are then try doing a SYNC from Kobo Desktop with the Kobo attached. This should in turn transfer the KePub version to the Kobo.