I had this happened to me, and I could not sync at all. EVerytime I deleted partnership and tried to restore the Sprite backup and soft reset, it would work fine, but if I reboot my PC or remove Axim from cradle, the same "no-sync" happens.
My workaround was as follows:
1. Make sure you have a Sprite backup (exe) preferable saved on SD card.
2. Hard reset your PDA.
3. Run the Sprite backup exe on SD card, it will ask you to re-register your Sprite program.
4. Create a new partnership. Ignore the old one, as its useless.
You're back to normal. I believe that it was caused by an errant program that screwed up somehow. Anyways, good for now.