i use the newest Piwik 3.1.1.
If you use the Dashboard over the Widget implementation (iframe) you can select/create the Segmentations you created. But they do not affect/data stastics do not filter always fall back to default "All Visits". If you direct login into piwik Backoffice it worked.
My Widget call example:
FYI: I quickly debugged and noticed this regressed in #11790 https://github.com/piwik/piwik/pull/11790/files#diff-4e4c0250d8a0ec9660276e396757f6efL1317
Only the hash is being updated I think but not the actual URL which it should here.