Also, the latest drivers (2020) seem more unstable on Sea of Thieves. Yesterday I was playing for a short while before Sea of Thieves just outright crashed... no warnings, just CTD.
The black lines are very jagged but very brief and don't happen all of the time. As described in the following post, it seems to happen at specific angles when reflections, fog/haze or god rays are involved. I do not recall this happening in drivers prior to December.
I'm not the only person getting this problem and sure enough they are all seem to be RX 580s, a card I am using (one person in linked post is a 5700 XT user). All in all, there's 5 people in that one post experiencing the same problem and I'd wager the post wasn't up long before it got buried.
Please try to address the jagged black line issue and improve stability for Sea of Thieves.
I'm using the latest Windows 10 64 build (not an Insider).
Ryzen 1600X (not overclocked).
Sapphire RX 580 Nitro+ 8GB (not overclocked).
16GB (8x2) DDR4 3200MHz
Tried 3 different drivers.
No other graphical anomalies in other titles.
No high temperatures.
I am playing using a FreeSync monitor (144hz) capped in game to 120fps (Vsync off in game). FS enabled in monitor settings and in Radeon software. Enhanced Sync and Anti-Lag is also enabled. RIS 50%.
I hope this info helps. I will edit this post and add additional details if I manage to catch a recording of it, but given that it's fairly infrequent (still very distracting and annoying though), that may be difficult to achieve.