To visually emphasize the middle of the bar, Perfect Layout re-ties notes which cross the middle of the bar by default unless there are symbols (articulations, expressions, hairpins, etc.) assigned to the removed measure position which would then become invalid or unclear (e.g. measure 3 in image 3).
There is also the option to only re-tie notes if the first tied note starts after beat 1 (activated by default).
In odd time signatures (e.g. 5/4) there will be no re-tieing.
Note: Perfect Layout
never adds extra notes. This means: not all cases of falsely tied notes are corrected (e.g. measure 5 in image 3).

Image 3: The re-tie settings of Perfect Layout
m.1: Only re-tied if "...After Beat 1" is deactivated
m.2: Always re-tied by Perfect Layout
m.3: Never re-tied by Perfect Layout because otherwiese the hairpin on beat 4 would become unclear.
m.4: Always re-tied by Perfect Layout
m.5: Never re-tied by Perfect Layout because otherwiese the hairpin on beat 4 would become unclear.