Solution
When [Shooting modes] is set to the [Auto] (, ) mode or the [Easy] ()* mode, [IS-Mode] is set to [Continuous].
In the [Auto] (, ) mode or the [Easy] ()* mode, the [IS-Mode] item is not displayed on the Menu screen, so the [IS-Mode] cannot be set. (Even the [Off] setting is not available.)
* Only applicable to supported models