How to detect variables like %s?

I tried following expression provided in the forum but it failed to detect “source: %1”, “target: 1”.

source: "(<%[$[:alphanum:]]+>)=1"
target: -<@1>

The following search detects those segments that contain variables like %s or %1 in target but are missing in target.

Source:"(\%[:alphanum:])=1"
Target: -@1
Search Mode: Regular Expressions
PowerSearch: On