I have noticed this problem for a long time even on separate PCs. I can add a torrent and when it picks up it can be jamming along at 500k a second. Then if I hibernate my Windows and reawaken later, the torrents will just never pick up again. My ports are open (green) and no firewall except Windows which I have permitted Bitcomet through. Sometimes I have deleted them and started over and they will pick up again. Weird to see 3 month old torrents stuck where they left off.