hard drive unable to stand by automatically

[chrome token]

One of my hard drives is unable to auto standby via auto standby feature of Disks utility. Its not being used, its unmounted, yet it cant automatically standby after specified time has passed. My other drive is able to standby fine, and my system is installed elsewhere.

Steps:
open Disks -> select HDD -> press "..." -> Drive Settings
enable "Apply Standby Timeout Settings"
wait for specified time to pass while drive is inactive

Expected behaviour:
Drive enters standby mode ("zzz" sleep symbol appears and drive spins down and stops)

Actual behaviour:
Drive doesnt enter standby mode

Additional info: Hard drive in question has been formatted and its single partition is named "Backup", as i use it for Timeshift backups. I only do manual backups, all automatic backups are disabled, and Timeshift is not open.

I think ive seen that drive auto standby itself one or two times before, but 95% of the time i have to do it manually.

[fringe steeple]

is it an internal drive? try unmounting it - use the stop button in Disks app. A drive is mounted if it shows a play icon inside it there, and a blue text link in the info under the diagram. In such case, a stop button will appear.

• can also unmount using the file manager. Right-click the device on the left, and choose 'unmount'

[chrome token]

all my hard drives are internal
im able to mount/unmount them ok
im also able to standby them manually

my issue is that one of my drives ignores automatic standby timeout
screenshot provided shows the enabled option
there is no disk activity to prevent it from going into standby mode
but drive just refuses to standby by itself

[fringe steeple]

show the APM tab of that

[chrome token]

i havent changed these settings for any of my drives

[fringe steeple]

turn that on n see.

perhaps that drive needs the "advanced" instruction sent by the OS