Some things in IDML import do not work yet:
I have exported an INDD to an IDML (as an example here only one page). In the first picture you can see the IDML in InDesign. In the second picture the same IDML was opened in APup. The following problems can be identified:
Text in placeholder text frames on the master are not transferred (below).
Button bar (master) was not taken over.
Arrow ends are missing.
Hatching appears too wide.
Text, especially the equal signs, appears differently.
I used beta 1.8.4.663. In the current release version, the image is placed outside the frame, so you can't see it.
IDML.idml