Anchored position z reads as missing in the Animation window

Steps to Repro:
1. Create a new or open attached Project
2. Hierarchy > right-click > UI > Button
3. Window > Animation
4. Select Button GameObject in Hierarchy
5. Click Create in the Animation window
6. Click on Add Property > Rect Transform > Anchored Position in the Animation window
7. Click on the arrow to expand Anchored Position

Actual Result:
Anchored Position.Z is missing

Note:
Same occurs for Max and Min Anchor properties

Expected Result:
Anchored position.Z shouldn't be displayed or a Default Value should be displayed

Environment:
Windows and Mac

Occurring with:
2019.1.0a13, 2018.3.0f2, 2017.1.5f1