The master preview in the preview bar seems fixed in 1174 but now the main edit area does not render any glyphs.
When in Text mode, all I can see is the blinking cursor, which I can still move around, and I can even select glyphs, which turns them blue. But no actual glyph shapes to be seen. The info box is still correct and the preview bar shows my string. In Select mode, Glyphs shows everything correctly for the current glyph (contours, zones etc) but nothing for the adjacent glyphs. Also, space bar for black-on-white preview does not show anything.
So, the conclusion is that the rendering of the black-on-white, filled preview of the glyph shapes in the main edit area is somehow broken.
I am on macOS 10.13.6 on an iMac.