What device are you using when installing GSI? And how did you install? Like what did you install and wipe? Just curious as I've dug deep deep a time or two on the GSI deal due to same issue I couldn't get my device to boot but there are so many different things that can be the reason. Please explain your install method and what all you flashed exactly and version of whatever recovery you're using.
I have Twrp 3.3.1-2 installed on my moto g7. This is the method I used:
fastboot --disable-verification flash vbmeta vbmeta.img
fastboot boot twrp
Wipe system, Data, Dalvik Cache, format Data
Fastboot flash system system.img (Bliss12.2)
Reboot to bootloader
Fastboot boot twrp
Install gapps (didn't install for me on 12.2)
Hope this will help you out. I have used this method installing 8 different GSI ROMs and have never had a problem.