When people reach out for a metaphor to explain how they are multi-tasking, the one that most easily springs to mind is a juggler continuously catching & tossing multiple objects in the air.
The juggler is juggling. No doubt about it.
Is the juggler multi-tasking?
If the multiple objects vary, does it become a multi-task? If the objects differ in shape, size or colour; do they create multiple tasks; a discrete activity in a class of its own ? A task so considered requires its own deliberate attention & specific action.
If the juggler is cycling & juggling at the same time, it is definitely multitasking. If the juggler is running & juggling at the same time, it is definitely multitasking.
When a juggler juggles multiple objects, it is not multi-tasking. The task is singular.