Terrain tree billboards corrupted on Mac intel integrated graphics in 2019.2

We upgraded our project from 2018.4 to 2019.2 (built-in pipeline), and are now having a strange problem with terrain tree billboard mipmaps -- only on Mac platform with Intel integrated graphics: they are usually corrupted, with multicolor noise instead of the billboard image. If I disable/reenable the terrain object, the billboards are regenerated -- occcasionally correct, but usually with some other noise pattern. I'm using an Intel HD 620 on a MacBook Pro, but have gotten bug reports from players on Macs with other Intel integrated graphics. Happens on MacOS 10.13 and 10.14 and 10.10.

I've reproduced this on a simple project and have submitted a bug report (Case 1211524), but hoping someone here knows about this and can advise how to fix it?