Quite recently, Anki drove me crazy over trying to find round brackets. Then I found a thread of earlier this year Cannot search for round brackets (closed, cannot comment there) - just to find out that this problem hasn’t been solved for over 5 years now.
However, here’s a workaround (to prevent others from going crazy):
Instead of trying
deck:current ( or
deck:current "(" you can use the regular expression escape sequence for hex character codes
\x. Round brackets have the ASCII character codes
\x29, respectively. Thus
will do the trick. Or, limited to a field:
deck:current myfield:re:\x28. Of course you’re dealing with regexes now. If your search term contains special regex characters, you’ll get unexpected results.
PS: Neither using a character class
[(] or trying to escape the bracket
\( did work. It seems that all expressions with unmatched brackets fail. In my opinion a working parser for search terms is essential and should be fixed before implementing some other fancy feature.
PS2: Damien Elmes let me know that
"(" should work now. I tried that, but it only works with
deck:current "(". If limited to a field
deck:current myfield:"(" it still doesn’t work.