Steps to Reproduce
- Go to Site Content -> Categorization -> Categories
- Edit the default Topic vocabulary
- Toggle Allow Multiple categories to No. Click on Save.
- Add 3 categories in Topic - A, B, C
- Create a new Basic web content
- Under Metadata category, click on Select next to Topic. This opens a new popup window which allows user to select the categories
- First select A, and then click on B.
- Click on Add
Result: You will see both categories for the article.