After posting my problem, I kept trying and solved. The solution is easy. Use the newest version of SP_Flash_Tool.
The version is 5..1804 at this moment. Everything was smooth on this tool. I tried with my Win8. Drivers seems successfully installed with the installer on needrom.com. Only the point I found is that when you plug Ulefone S8 pro
after click 'Download' button on Flash_Tool, better detection is expected if you keep pressing the Vol Down button
of the smartphone then connect the USB plug.
I am now V3.02, yes you can go to V3.03 but a post on needrom.com says there is some problem with V3.03. If the
problem will be solved, I will go to V3.03 (or V3.04 at that time?).
OK, good to see that you solved the problem by using latest version of flashtool.
What I am facing on both versions is following.
Scheduled On/Off does not work when the phone is connected at charger.
I am using this feature with the phone is connected at the charger to automatically switch on/off during night.
On all my old Android 6.0 devices this works great. However in the Ulefone S8 Pro the scheduled On/Off does work only when the timer is set at arround 1h. Setting up to 8h and connecting to the charger, the phone does not wake up and switch on.
It seems to be a problem of the Doze, battery mode of Android 7.0.
Can someone try this feature?
Thank you.