I ran into a problem with Lenovo Thinkpad T470p, but it also happens on some other models. It didn’t let me use the Integrated Webcam on Windows 10 anymore. Luckily I found the fix!
Looks like it is a problem with the built-in Realtek camera hardware.
Windows Key + R, type regedit, and press EnterHKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows Media Foundation\\PlatformPlatform folder and select New -> DWORDEnableFrameServerMode, and change its value to 0HKEY_LOCAL_MACHINE\\SOFTWARE\\WOW6432Node\\Microsoft\\Windows Media Foundation\\PlatformSource: Lenovo Forum
There are also some other suggestion on the Internet:
Settings -> Privacy -> Camera).