I've added the draw.io add-on to our Confluence cloud service (add-on version 1.3.3-AC). I've used draw.io a lot and don't have any questions regarding how to draw diagrams etc.
In the add-on documentation video it's shown that after adding a diagram the dimentions of it can be modified just like it is done for regular images - in page edit mode just click on the object and a layer pops up with the selections. Now the case is that the layer indeed also appears while clicking on a draw.io diagram, but the sizing buttons are missing (it has just "Edit" and "Remove"). This is how it looks like:
confluence_draw.io_tst.png
