Depois de pesquisar bastante, lembrei-me que instalei powernap .
sudo powernap-action -l
[disabled] 01cpu_online - sh: 1: /etc/pm/power.d/01cpu_online: Permission denied
[enabled] 00flag -
[disabled] usb - sh: 1: /etc/pm/power.d/usb: Permission denied
[disabled] video - sh: 1: /etc/pm/power.d/video: Permission denied
[disabled] eth_speed - sh: 1: /etc/pm/power.d/eth_speed: Permission denied
[enabled] usb_autosuspend - Auto suspend USB bus to save power.
[enabled] cpu_frequency - Lowers the CPU frequency, changing the scaling governor from ondemand to powersave.
[disabled] kms_powermode - sh: 1: /etc/pm/power.d/kms_powermode: Permission denied
Uma das opções que eu tinha ativado foi
[enabled] usb_autosuspend - Auto suspend USB bus to save power.
Por isso, corrijo o problema desativando usb_autosuspend.
sudo powernap-action --disable usb_autosuspend
Então agora
[disabled] usb_autosuspend - sh: 1: /etc/pm/power.d/usb_autosuspend: Permission denied