This command (Ctrl+F5) works like Refresh, but additionally re-reads the contents of every compared file pair from disk, ignoring the content hash cache for this one pass. The freshly computed checksums replace the cached entries, so the cache is rebuilt for the compared directory trees.
Use it when file contents may have changed without a change in file size or modification time — for example after tools that restore timestamps (backup or synchronization software). A normal Refresh trusts the cached checksums of files whose size and modification time are unchanged.