The problem is with 2DPlatformer package from AssetStore (https://www.assetstore.unity3d.com/en/#!/content/11228)

Regression from 5.6.0a5 (also works correct in 5.5.0p3)

We have 2 objects with sprites with the same value of "Order in Layer = 6":
- "env_BigBen" (bacground)
- "Bus"

"env_BigBen" is a static object, but "Bus" is created dynamically in run time and I expect that it will be shown in front of the static "env_BigBen"(it works in this way in 5.5.0p3 and 5.6.0a5), but starting from 5.6.0a6 and in 5.6.0b3 "Bus" is behind "env_BigBen" - so the behaviour is changed between these versions (according to devs it is expected !!!) - so we need to fix the project
--- please see attached .gif in comments ---

How we can reproduce it using the example you attached
1 Open attached project and scene "Level"
2 Press Play
Actual results: "Bus" objects appears behind the "env_BigBen" in 5.6.0b3. But when open this project in 5.5.0p3 or 5.6.0a5 - "Bus" objects will be in front of "env_BigBen"

Expected results: the behaviour should be the same in both 5.5 and 5.6 - to achieve this we need to fix the package - probably update the "Order in Layer = 7" for Bus and Car sprites