Bootcamped Win 10 is not starting - hard drive not found

I installed Win 10 on iMac 27" 2017. Frist run was fine, BC drivers were installed, apart from Magic Mouse 2 and numerical part of my Magic Keyboard.

I transferred Windows apps etc. from my Win 7 running on MacBook Pro 2010 and form installing Win updated I restarted my machine. The result was Recovery Screen. There was no help going back to one of the recovery points, it ended up with restart loop.

I decided to Return to Factory Settings. That was fine and I installed my BootCamp drivers manually from USB drive. I checked Apple Updated and installed latest Wifi and Graphics drivers. As I was asked, I restarted my machine. And the very same result.

Scanning my drive for fixable errors during pointed me to log files (SrtTrail.txt). Once opened in macOS, it shows following:

"

Startup Repair diagnosis and repair log

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Number of repair attempts: 1

Session details

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System Disk =

Windows directory = C:\WINDOWS

AutoChk Run = 0

Number of root causes = 1

Test Performed:

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Name: Check for updates

Result: Completed successfully. Error code = 0x0

Time taken = 0 ms

Test Performed:

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Name: System disk test

Result: Completed successfully. Error code = 0x0

Time taken = 750 ms

Root cause found:

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A hard disk could not be found. If a hard disk is installed, it is not responding.

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"

I'm able to run Win Safe mode and install drivers (if they are exe files) and browse my BootCamp drive on macOS. So there is no chance, that my drive is not connected.