It looks like if you update the name of a Portfolio-linked JIRA Version outside of Portfolio, and then do a sync in Portfolio, Portfolio changes the name back.

• Create a JIRA Version (Name "Release 4/15")
• Create a JIRA Portfolio Release
• Link them together in JIRA Portfolio
• From the JIRA Project Admin area, change the name of the Version (From "Release 4/15" to "2.1.0")
• Back in JIRA Portfolio, hit "Apply Updates"
• Notice the JIRA Version name has been changed back to "Release 4/15"

Workaround Delete the link in JIRA Portfolio, and add it again

Related Issues There also doesn't seem to be a way to resync these JIRA Portfolio with changes from outside Portfolio manually. See JPO-156