Failure on dismount a container file on sleeping external USB drive

[andry81]

1. External USB drive is connected through AgeStar 3U2B3A
2. Container file on the drive is attached
3. Drive is sleeping
4. Try to dismount the container

VeraCrypt time to time fails to dismount the container with an error dialog said something Failure dismount and immediately force dismounts the container (popup balloon message).

Expected behavior

Keep waiting the drive spin up.

Observed behavior

Force dismount on some event or timeout.

Your Environment

Please tell us more about your environment

VeraCrypt version: 1.26.7 64-bit

Operating system and version: Windows 8.1 9600

System type: 64-bit