I have a Mac Pro 3,1 with an ATI Radeon RX580 8GB graphics card, a dosDude Catalina (10.15.6) install on an internal SSD and and a Windows 10 Pro (latest Version and updates) install on an internal HD.
Both macOS and the Windows work fine along with all parts of the Mac. As I a have the Radeon card I do not have a boot screen until either Catalina has mostly started up or Windows has started to boot, so I cannot change the booting by holding down the Option key.
I previously ran El Capitan instead of Catalina, and with that I had installed in Windows the Boot Camp 4 drivers, which allowed me to select macOS from the Boot Camp Assistant and reboot from Windows into El Capitan. From El Capitan I could select the Windows drive in the start up disc control panel and reboot into Windows.
However, since upgrading to Catalina, I can still select the Windows drive in the start up disc control panel and reboot into Windows. However if I select macOS from the Boot Camp Assistant and reboot the Mac, it always reboots into Windows.
My current work around is to shut down, remove the Windows drive, reboot in to Catalina, select Catalina in the Startup Disk control panel, reboot into Catalina, shut down, re-install the windows drive, start up and it starts up into Catalina again with the Windows disk mounted. I can then just select the Windows drive in the start up disc control panel and reboot into Windows when I need to.
From what I have read it's an issue with boot camp not liking the APFS file system Catalina uses. I have also read that a newer version of Boot Camp would fix the issue. I have upgraded Boot Camp to version 6, but this cause other issues in Windows and in the end I had to format the windows drive and re-install it from scratch along with the Boot Camp 4 drivers.
Can anybody tell me how I can get this issue sorted out so I can just switch using Boot Camp?