In the following example, page number entries in the index are not
displayed when a blank line is inserted in the text, but do appear
without that blank. This happens with both the current 20140316
standalone beta and with TL2013.
(I noticed this constructing MWEs for other index register problems.
It is likely not a problem in real life, but may provide insight
into other issues.)
\starttext
Why do the entry page numbers disappear when a blank line
follows
this line, and reappear when the blank line is removed? (Current
beta and TL2013.)
\index{AA}
\placeindex
\stoptext
--
Rik