Tag Reference lost during moving/merge operation

Problem Statement --> AEM Tag references are lost when we do move/merge operation via tagging console.

Steps to reproduce the issue

Step 1 -> Create the following tags
1. Tag A
2. Tag  A --> Leaf 1
3. Tag B
4. Tag B --> Leaf 1 Renamed

Step 2 -->  Adding tag to a Page
1. Open any page properties.
2. Add Leaf 1 tag
3. Save the properties

Step 3 --> Navigate to Tagging console
Step 4 --> Select Leaf 1 Tag and check it's references, it should show the page which was created in step 2.
Step 5 --> Perform merge operation on Leaf 1 to Leaf 1 renamed.
Step 6 --> Select Leaf 1 Renamed Tag and check it's references, it should show the page which was created in step 2.
Step 7 --> Select Tag A and Merge it into Tag B
Step 8 --> Repeat Step 6 now we are not able to see the tag references.

Questions 1. Why tag references are lost after executing step 7 ?
Question 2. Is there any guidelines by Adobe to perform move/merge operation on tags ?
Question 3. How to check if page references are lost before performing move/merge operation ?