Hi Megan,
I had this problem with my Asus VivoBook pro N552VX before .
'''You can try a several things:'''
* BIOS update
* Reinstall battery drivers - Usually Battery control method driver
* Reinstall 3rd party software for control management
* Windows Reinstall (factory reset -just only idea)
But that’s all. I’ve done a lot of things and my last step was a new battery. A lot of issues are, that Windows is showing “plugged in, not charging”, but if you get “plugged in, charging”, it’s usually hardware issue, in this case, battery.
'''Batteries are having an only limited warranty, always it’s 12 months and the lifetime is decreasing a day to day.'''
If the battery is newest then 12 months, you can contact your laptop dealer and ask for a refund or exchange, otherwise (I know, it’s difficult, expensive and you won’t be happy) you have to order a new battery. (and If the issue will still occuring, you can return battery to the shop for some reason like “incompatible”), but on 99%, your issue will be solve.