While I don't yet have experience with other android devices... like many of you, I have vast experience with sync issues... Hopefully the info below may help some, if not all. It is a copy of what I replied back to a support staff of CompanionLink. They are not without issues either...
Note: I did buy a 3rd party software (CompanionLink) because I still want the direct USB sync for privacy reasons... mentioned below...and similar to the other user post that had helped me...
The reply was...
Thanks, but what I have found "in action" is actually more similar to the experience of another user (see link below).
I have ultimately found the steps I listed below as well to work without issues consistently...
Maybe consider updating your support pages to provide this - it has been frustrating for at least a few months of resets and repeated one way "syncs"... and I have been on the verge of returning to a blackberry to be able to have a proper confidential and direct sync of data without going through a 3rd party indirect sync no matter how much it is promised to be secure (enough company's have been hacked and the end-user only really gets a notice and an apology while the private data still gets taken...)
here's the link that has helped me the most to figure this out...
http://androidforums.com/android-applications/402536-usb-sync-all-outlook-any-crm-data-android.html
I have (Motorola droid maxx hd, Android 4.4.2, DejaOffice 3.1.2, CompanionLink 5 - may be "fixed" in 6)
These are the steps I now take that I have ultimately found to work consistently and not cause issues (so far, and if followed religiously):
--establish any preferred settings for Sync in CompanionLink on the PC and in DejaOffice on the device
--ensure CompanionLink and MS Outlook are open (active and running) on the PC
--connect the device to the PC via USB cable
--turn CONNECT AS Media Device (MTP) "ON" by selecting "Settings" --> then "Storage" --> then "USB computer connection" from the menu drop down (usually in top right corner) --> then ensure box for "CONNECT AS Media Device (MTP)" is checked "on"
--open DejaOffice from main app icon and tap Sync icon (I no longer use any icon shortcuts at all)
--IMPORTANT: when Sync is finished, first tap Exit icon in DejaOffice, then turn "OFF" the CONNECT AS Media Device (MTP) = uncheck the box in settings section as above, then also Exit CompanionLink on the PC, then disconnect device from USB cable
--use device as usual, then repeat these steps every time to sync with Outlook through CompanionLink / DejaOffice
And yes... some of these steps may seem or actually be unnecessary, but having it function is more important to me than skipping an unnecessary step.