I've got an atlas in QGIS 3.2 and also 2.18. There is a main frame showing a map with points. Underneath there is a table with further information about the points.
If there are many points, the table extends to a 2nd page. From this point on, there is always a 2nd blank page. I tried to set
Don't export page if frame is empty with no result. Maybe this option is being overridden at some point (it is automatically unselected after turning the atlas off/on or exporting).
Tried many more things. Now I'm stuck.