DO Medical/dental benefits get declined for a person if his kid turns age 26 and he looses coverage

Summary:

We are seeing a behaviour where a person has a single kid turning age 26 in Feb and we are trying to add the manual admin event to get his kids removed from the coverage but the system is directly putting his Medical and dental plan in decline status after evaluation .Is this normal behaviour for loss of coverage.

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I was expecting the coverage to come back as employee only

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