Full model name of your primary display, please.
It can happen if problematic monitor has QHD resolution(2560x1440) and you are trying to use single link DVI cable.You need dual link DVI cable in this case.
Its an Acer H236HL, 1080p monitor.
INFORMATION REQUIRED WHEN POSTING A QUESTION Provide your full system info!
Leave only one monitor for this operation (Acer H236HL)
1.Delete C:\AMD folder
2.Uninstall all AMD software and clean your system in safe mode by DDU program and install 17.2.1 driver
3.Then reboot and plug your second monitor ,checking that Windows has installed correct driver for each monitor
4.Maybe you need to try another HQ DVI cable for this monitor. If it works with one monitor it doesn't mean that it must work with another.