Honestly, I don't know without comparing the preloader from the flashable version to the OTA version. I thought there's only two preloader versions for Android 6 and Android 7 as a complete Android 6 TWRP backup doesn't work on a Android 7 preloader, you get a nice black screen, download didn't work so I had to do a format and download. What's strange is, I've never had that error, and I can't find any info on it. I think it could be the drivers.

Uninstall and remove the current mediatek preloader usb vcom driver and any remnants in device manager. In device manager(right click This PC or My computer), show hidden devices and remove and uninstall all mediatek devices under ports and install the newest drivers;

Windows 7, http://drivers.softpedia.com/get/MOBILE ... ws-7.shtml

Windows 10, http://drivers.softpedia.com/get/MOBILE ... s-10.shtml

When flashing phone off, select scatter file, select download on menu, press download button, connect phone.

The Twrp pack you provided me, was that for Android 6 or Android 7.
I was looking for the Twrp pack for Android 7!

Android 7. I just unpacked and repacked the Android 6 recovery with the 20170708 Android 7 kernel, recovery fully works.

Try this. Edit the scatter file with notepad++ and delete the preloader partition region from " - partition_index: SYS0 " down so it starts with "- partition_index: SYS1" .

Flash the recovery I did with the edited scatter file.

If it works do a FULL TWRP backup(Don't select System Image, it breaks the phone and you have to restore from TWRP again), save it on your phone or external sdcard and then save it somewhere safe off your phone like your PC.

Format and download with spflash with stock unedited 20170708 ROM, then flash TWRP recovery.

Do a full restore from the TWRP backup. Root your phone.