If they have no other dependents and you filed the tax return for the daughter, you may be forced to paper file which could be a PIA due to IRS shunting paper returns/correspondences to the side. But you may not have a choice. 

Ive seen other people mention it happening....Ive never had it happen.

I've encountered the same issue...I also prepare the dependent's return, have the correct boxes checked & verified that the dependent's standard deduction was that of a dependent child. I am curious as to whether several people are encountering this issue due to a computer glitch or if my taxpayer's dependent's SSN has been stolen.

Have you found a work around? Or will I have to send by mail?

No workaround determined. My clients had to paper file.