#1 - June 9, 2016, 9:44 p.m.
Blizzard Post
Posting these to the Bug report forums as well for visibility:

During some parts of the invasion there's a ground based effect (Fel Creep). If you have your graphics set very low (1 or 2) this green effect doesn't display cleanly. It's visible, but will have patches missing or rough edges. Just something to be aware of while testing this content out.

Additionally, once an invasion starts, the zone map will say it is Under Invasion but there will be no timer visible.

The map icons for Legion Invasions are not visible at the continent or world level. To see if an invasion is active, you'll have to directly click on the zone map for the area. This applies to all six zones that are eligible for Demon Invasion:
Hillsbrad Foothills
Dun Morogh
Northern Barrens