1) You cannot have more than one Custom DIV on a page! They are always referred in code as “externalhtmlobject” instead their HTML names (“other52”, “other888” etc), so all instances but the last one are overwritten.
2) They miss their height attribute! Their CSS always includes position:absolute, top, left, width, all of which can be set in Lectora.. but no height property! So the height is always 0.
As a workaround for #2, it is possible to include whole new div in that div and write any code in it, but it means that the height should always be specified manually, kinda opposite of what rapid authoring tools should do. And there is no workaround for #1 unless I write out all my divs inside that one custom DIV, which is again, entirely opposite of “rapid authoring tool” idea.