Description of problem:
You are unable to add properties to a new tag without first saving it.

How reproducible:
Always on Next and the Production versions

Steps to Reproduce:
1. Go to either UI
2. Select Tags on the left
3. Click "Create new Tag"
4. Click "Extended Properties"

Actual results:
The loading icon appears and never disappears. Inspecting the requests sent, it looks as though a request to get the properties is never sent.

Expected results:
The available properties should be displayed so that they can be added to the Tag.

Additional info:
Note that this only occurs for new tags. If the tag already exists then you can add or remove the properties.