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.

Code:
+++ log4j.properties    2011-11-15 05:30:18.000000000 -0600


@@ -94,11 +94,11 @@
 log4j.logger.net.spy.memcached=WARN
 
 log4j.additivity.zimbra.sync=false
-log4j.logger.zimbra.sync=INFO,SYNC
+log4j.logger.zimbra.sync=DEBUG
 log4j.additivity.zimbra.synctrace=false
-log4j.logger.zimbra.synctrace=INFO,SYNCTRACE
+log4j.logger.zimbra.synctrace=TRACE
 log4j.additivity.zimbra.syncstate=false
-log4j.logger.zimbra.syncstate=INFO,SYNCSTATE
+log4j.logger.zimbra.syncstate=DEBUG
 log4j.additivity.zimbra.wbxml=false
 log4j.logger.zimbra.wbxml=INFO,WBXML
 log4j.additivity.zimbra.milter=false