Statistics don't work for filtered decks

[ttempe]

From Iain Dalton:

What I did: I made a filtered deck using the search note:"Chinese character" (the name of the note type I use for characters I've learned how to write), then went to that deck and clicked on Show statistics.

What happened: All the regular statistics work, except forecast; but Chinese characters and Chinese Vocabulary show no data, and report "0 known characters/notes."

What I expected: I expected to see the charts filled out the same as if I had all my characters stored in their own deck and were looking at the statistics. I like to review everything together, but I also like to check how many characters I know how to write, which is less than all the characters I can recognize, so I can't just check the main deck statistics.