PC can't find OnePlus 7T driver during bootloader mode

I came so far with the easy installer untill it says: restart the device in bootloader mode.
The phone is then in bootloader mode but then it’s stuck.

My assumption is that the computer (windows 10 pro) doesn’t find the driver for the device anymore which is weird since it found it in normal mode before.
I already downloaded the driver for the OnePlus 7T and ran it, but nothing changed and the device is not found in bootloader mode.

the model ist a HD1903 and is thus supported for /e/OS

I’m stuck with the process and would be very grateful for help. Any ideas?

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

It is common for some devices to have a Windows driver for normal use, but which does not support fastboot; a composite driver is needed but Windows update will not look for it unless requested.

You can try to connect the device to your PC, open a Device manager window, check for no “:warning: Problem device” in Device manager.

Open a terminal and run

adb devices

the device should identify itself; check for no :warning: in Device manager, if found run Windows update.

Now boot into fastboot mode. Run in terminal

fastboot devices

the device should identify itself; look for a :warning: in Device manager, if found run Windows update.

If adb and fastboot are not installed on your PC you can simply try to run Device manager and Windows update alongside Easy Installer.

Having seen a log in this post OnePlus 7T stuck at bootloader screen on easyinstall - #5 by aibd, I wonder if Easy Installer might be booting the device to Bootloader, but fastboot was the intention and required.

Is it possible that another button press is required on the device to accept / confirm engagement of fastboot mode ?