Nexus Repository 2 has a facility to log additional details about javascript-related errors using a query param.
Load the Nexus UI using a URL with ?debug=true
appended.
Example:
http://localhost:8081/nexus/index.html?debug=true
Reproduce your error and examine your browser's Developer Console for javascript tracebacks and errors. Supplying these tracebacks to Sonatype Support staff can help us solve the problem.