I had problems with the CPS software version 1.16 when trying to update the firmware. The window when selecting Tools -> Firmware just didn’t open. It turns out the software seems really buggy.
Solution: When CPS is running, open a File Explorer and go to “C:\Program Files (x86)\Anytone\D578UV_1.16\” and double click on UpdateQX_Firmware_Update.exe.
The window will now open and you can continue with the firmware update.
Thanks to Ronny/SM7IKJ who gave me to the solution.