Disk Not Ejected Properly -- AGAIN AGAIN AGAIN AND AGAIN...

New M4 mini. Computer gives the same "disc not ejected properly" message it has for years on my old Pro. Changed cables, settings; nothing worked. Bought 2 difference powered hubs. One junk, the other looked OK with5V3A power supply. 'Thought' the problem might be the computer power supply being unhappy when my 4TB SSD was called for a Backup so I connected the 4TB drive to the dock. NO, no, no! Got like 40 "disc not ejected properly" messages and they just kept coming.

Took 2 devices off the M4; keyboard and printer and connected them via USB on the dock. Plugged both 1TB and 4TB drives into the M4 mini and, like magic, no more "disc not ejected properly" message. Sleep then wake; no message. Restart; no message. Shutdown then Start; no message.

Caveat = YET!