Do you have Allow round bracket grouping enabled from Tools -> Options -> Search?
If so, please disable this option.
When this option is enabled, ( and ) are treated as < and >
When this option is disabled, Everything should treat ( and ) as literal ( and ).
Everything uses < and > for grouping, for example:
<sonic tails> | <mario luigi>
In this example, Everything will search for:
(sonic AND tails) OR (mario AND luigi)
without the < and > grouping, Everything would search for:
sonic AND (tails OR mario) AND luigi