I'd open the/a file in FM9 and save as MIF, then open the MIF in 15 and see
if that makes a difference.
Then check a couple things: I'm thinking either the master page assignment
is getting trashed, the pagination (alternate left/right) is getting
trashed, or the text frame has gotten deleted.
Since I upgraded from FM9 to FM2015 unstructured on Win10, my every
other page is a blank (except for the page background). Text Flow A
exists only on alternate pages and when I turn on the text flow dotted
lines, it is revealed that every other page has no text flow frame at
all.
