Background operator doesn't work correctly

[kirpichik]

The statement of the process start in the background doesn't work correctly.
Example:

(*_*)$>sleep 100 &

[1] 3455

[1] Done sleep 100
(*_*)$>

The process is started and immediately terminated.
This process isn't displayed in the work list after that.

[kirpichik]

Also, although it is printed that the task is completed, it remains in the background.
You can check it using the ps command.