How to reproduce:
1. Open given Unity project
2. Enter "test" scene
-- Notice that canvas is disabled
3. Enter Play Mode
--Notice that canvas is enabled
4. Expand canvas in the hierarchy
5. Notice that 10 GUI objects with Rect Transform are instantiated in (0, 0, 0) position

Expected result: 10 GUI objects should be instantiated in random positions
Actual result: 0 GUI objects with Rect Transform are instantiated in (0, 0, 0) position

Regression first introduced in: 2017.3.1p1
Reproducible with: 2018.2.0b2, 2018.1.0f1, 2017.4.1f1, 2017.3.2f1
Not reproducible with: 2017.2.2p2, 2017.1.3p2

Note:
It's not the same bug which can be solved with RectTransform.ForceUpdateRectTransforms