The Nexus UI is caching content which is can be confusing for the end user, when expecting changes.
I reproduced this issue with the following steps.
1) Using the Nexus UI Browse Tree, navigate to a maven component metadata and click link to view the maven-metadata.xml
2) Delete one of the component version.
3) Navigate to a maven component metadata and click link to view the maven-metadata.xml. It has not changed.
4) Use curl to download the metadata and can see that it has changed.
We should set the following headers in the response to prevent this (see
Cache-Control: no-cache, no-store, max-age=0, must-revalidate