Search across many types of one index suddenly stopped working

I was using elasticsearch 0.19.2 on production server for 2 months and one
day I've suddenly discovered the next problem.
Search across multiple types works incorrect sometimes.
Example:
If I do requests like:
curl -XGET "http://127.0.0.1:9200/fts/comment/_search" -d "{my_query}"
curl -XGET "http://127.0.0.1:9200/fts/category,comment/_search" -d
"{my_query}"
I get some documents of type comment, as expected
But if I do one of the following:
curl -XGET "http://127.0.0.1:9200/fts/category,product,comment/_search" -d
"{my_query}"
curl -XGET "http://127.0.0.1:9200/fts/_all/_search" -d "{my_query}"
curl -XGET "http://127.0.0.1:9200/fts/_search" -d "{my_query}"
I have no any documents of comment type in the results, although the query
is the same, so comments should match.

About one month ago everything was working as expected, and there were no
any changes or updates performed during last month, except addition of one
non-data slave cluster node located on other server. Can it be the reason?
Also I had tryed to update elasticsearch to 0.19.9, but it didn't help.

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