How do release start and end dates work in Portfolio?

[Brad Chodos-Irvine]

there are options for setting fixed dates or letting portfolio calculate the start date for you... 

the fixed option is the only one that actually seems to work. The other options have no affect. I feel like I am missing something obvious but has anyone else had luck with this feature? 

[Bhushan Nagaraj]

Hey Brad,

Are you referring to the start date and end dates of releases?

If yes, having a fixed start and end date will allow you to identify if all the items within this time period can be released on schedule. 

Having Portfolio calculate this for you is a way to identify the possible release date with all the items you would like to complete.

Please take a look at https://confluence.atlassian.com/jiraportfolioserver/configuring-release-dates-802170565.html

Regards

Bhushan

[Brad Chodos-Irvine]

Thanks - yes I understand generally how it supposed to work. But the different options did nothing to change dates really or show me a different outcome.
However, it turns out that some of my epics had start and finish dates already set by someone unbeknownst to me, so it was influencing the schedule outcome. Once I removed those constraints it solved my issue. Thanks!