In the context of support case 78561, it was suggested that the below change to 7.1.3 would enable detailed logging. It doesn't -- in fact, synctrace.log is still empty, and sync.log stopped logging entirely.
I see two previous unanswered questions on this topic, but they were a while ago.
My immediate problems include an account that causes a server error if ActiveSync requests a full calendar sync (but syncing "last 6 months" works) and an Android device that fails to sync calendars on one specific account. It would be really nice to be able to get some answers.
+++ log4j.properties 2011-11-15 05:30:18.000000000 -0600
@@ -94,11 +94,11 @@