it was late last night when I wrote that so I'll explain a little better how I got a stable system.
I had problems with both Linux and Windows when I put together this computer before even using libreelec, all we're graphic related and and one occasion the same problem was present on both fedora and windows so it seems certain things are shared between os'es.
I had to use fedora as anything below kernel 5.0.x Linux wise would not boot on my system.
Then came the agesa 1.0.0.6 pinnacle update and all the problems we're fixed and everything became stable.
As more bios updates came out and I updated to them I started getting strange fan behaviour and the system becoming a little unstable again (random freezes and if I played a video on YouTube on windows when I would go full screen I would get audio but the screen would just be green).
So things were clearly bios related so I contract gigabyte support with this issue and they were a great help. Basically latest is not greatest these days it appears and it worked for me.
The tech support told me there is no benefit being on anything higher for the bios version than the final version of pinnacle PI as anything after that is just updates for amd 3000 series or up and coming processors.
I questioned that as the latest bios also stated "improved boot times" but they said that's irrelevant to me as that's improved boot times for amd 3000 series not my 2200g.
Also as newer processors come out they will have to remove older generation support as the bios is limited to a certain size, this means the motherboard will support a wide range of processors but will require different bios versions depending what you use.
I was advised to use bios with agesa 1.0.0.6 pinnacle PI as this is the final version for 2200g anything after that is just support for newer stuff.
Followed there advise updated drivers from amd and everything works fine now.
Also Ubuntu since updated to to kernel 5.0.x so that also now works.
Also I need to add for me libreelec didn't work until the beta reached kernel 5.0.x which I believe was libreelec 9.1 the old 8.2.5 didn't work for me and wouldn't boot just like any other Linux distro below kernel 5.
Since 9.1.501 le has been solid for Me, had a few boot warnings but one was because I had virtualisation switched on in my bios and the other is apparently safe to ignore as it's only a warning and fixed in later kernel.
Hope some of this can help you as it can be frustrating.
But the fact my setup is pretty much same as yours (I think) and works fine you should be good if you follow what I did.
Rob