It only allows a transform operation after selection
After the last update 18/11/2018 it seems to be improved, but not completely solved. Still transforms accidentally.
by comparison I tested the behavior using the app Graphic and the experience is much better. And they don’t standardize the app as a PRO tool. So AD for iPad is now on my opinion below of the line of amateur app.
I really recommend the Affinity devs to test the competitor Graphic for IPad.