same here. The left part of the screen is basically stretched/distorted below the first two inches or so.
Our integrated Vega is simply not fully supported yet, and making it work is a bit of a gamble right now.
It worked (but sloooowly) with 4.15 kernel and Mesa 17.3, with 4.16 and Mesa 17.3 OR 18 RCsomething I get that messed up screen as well.
Funnily it SOMEtimes does not happen, but 90% of the time.
Not just in Solus, I tested Ubuntu Budgie 18.04 daily snapshot as well and others.
Guess we will have to be patient until 4.17 is out, it is said to have proper support for the Raven Ridge processors like our 2400G
AMD Ryzen 5 2400G on Asus Prime A320M-C R2.0