Same issue as OP here (screenshot: https://d.pr/i/xb2tek). I have the application running on Windows and Linux systems, but it only seems like this is an issue on Windows (as far as I have noticed). It will hover around 25-30% for about 15 minutes each time (even if fully synchronized), it's not constant and I have not tracked how often it takes place, but I have noticed it does occur several times during the day .
Main Sync:
- 14,506 Files, 6,863 Folders - 1.82GB
- 240,427 Files, 35,142 Folders - 14.4 GB