I have experienced a sync issue today.
I will call A my android phone.
I will call D my desktop computer
I will calll L my laptop.
1. I opened L to read my tasks, then went offline.
2. I made some changes on D and A, both being online - everything synced well.
3. I added tasks on L while offline.
4. I added tasks on A while offline.
5. I connected A to the internet. Tasks added and completed while offline synced normally.
6. I connected L to the internet. Tasks addes while offline synced normally, but a task I had editied in step 2 was not updated. I had removed the due date from this task in step 2. This task still appears with a due date on L, but not on A.
Current status: Task appears with due date on L and D (which means an outdated information was propagated to D), it appears without due date on A (outdated information was not propagated to A.)
I hope this helps you work on the sync issues you have been having.