To reproduce:
1. Open user's attached project
2. Enter Play mode to build the Atlas
3. Check SpriteAtlas.spriteatlas packaged sprites' order via any text editor or Inspector window's debug mode
4. In Project window, select Sprite A
5. In Sprite's Inspector window, Override for PC: change Max Size to 32 and Apply
6. Repeat 2 and 3

Expected: Sprite indexing ordering in .spriteatlas file doesn't change
Actual: Sprite indexing ordering changes, also resulting in meta files differences depending on which platform is selected

Reproduced in: 2017.3.0a4, 2017.3.1p4, 2018.1.0b13, 2018.2.0a8
Not reproduced in: 2017.2.2p2, 2017.3.0a3

Note: since regressed release, sprites have been arranged in atlas according to the size, however this is inconvenient when having platform-dependent Sprite settings