How to reproduce:
1. Open the attached project "tileBug.zip"
2. Open "SampleScene" Scene
3. In the Hierarchy window, expand "TilePrefab" > "Grid" and select "Tilemap" GameObject inside of it
4. In the Menu bar, go to Window > 2D > Tile Palette and dock the new window anywhere
5. Focus on the Tile Palette window, press "B" on the keyboard to select "Paint with active brush" tool
6. Select any tile and hover the mouse on the Scene View
7. On the keyboard, press Shift + Curly Bracket

Expected result: the flipped tile is rendered
Actual result: the flipped tile disappears

Reproducible with: 9.0.0-preview.35 (2020.1.0b13, 2020.2.0a17)
Not reproducible with: 9.0.0-preview.14 (2020.1.0a23, 2020.2.0a17)
Couldn't test with: 2018.4.24f1, 2019.4.3f1, 2020.1.0a22 (9.0.0-preview.14, 9.0.0-preview.35 not supported, no Sprite Lit Graph)