Daisy chained My Book Pro - keeps disconnecting

Hi there,

Setup is as follows;
2x My Book Pro daisy chained (each in RAID1)
macOS High Sierra
Connected via Thunderbolt (Apple thunderbolt adapter).

I’m having a problem where the daisy chained unit keeps disconnecting (showing the not properly ejected notification). I’ve changed out 2x My Book Thunderbolt Duo’s for this setup, which never experienced this issue.

Any suggestions?

Thanks.

You may check after the upgrade the firmware of the My Book device and then check in daisy chain connection.