I have two external monitors connected to my MBP 16" and when I take the MBP out of sleep mode one of the two monitors never connects back up. One monitor is connected with USB-C to USB-C and always connects when the MBP comes out of sleep mode. The second monitor is connected with USB-C to DP cable and this one remains black until I disconnect the cable for two mins then plug it back in (< 2 mins and the OS doesn't seem to see the monitor was disconnected and won't reset things.) When I look at the displays in the system settings it's only showing the built-in and the one connected on USB-C. Each monitor is connected directly to the MBP spread between the two separate bus connections for the USB-C/Thunderbolt.
I've also tried using a OWC dual DP adapter which only made problems even worse as I had to restart the MBP each time I reconnected the monitors and only could get one of them to work at a time regardless.
I'm running 10.15.4 OSx and I have the AMD Radeon Pro 5500M 4 GB graphics card.
I'm really new to the Mac world and I'm struggling to find a working solution to the issue besides what others have posted for answers which is disconnect the cable and reconnect it. One additional answer that someone posted was upgrading the drivers but that was for the docking station they were using.
Why would only one monitor restore after being resumed from sleep?