I was not able to reproduce the issue using Chrome version 53.0.2785.143 on macOS 10.12.
Please provide step by step instructions to reproduce the issue.

Same versions I am using. I have just rebooted to make sure all is fresh and it still happens.

Load 'View Issues'. I have a filter set up that is used 99% of the time to reflect our current development version.

On page load - click on the 'close up' arrow on the filters section head. It closes up.

Now - it doesn't matter what happens next. The next time 'View Issues' is requested, the filter section is loaded open again.

OK - that's weird.

I tried something else. I logged out. And then logged back in. And now it holds. Could it be the first login had not saved the pref or cookie or whatever you use? And odly I was not logged out after the reboot...

But it seems fine now.

I tested a bit and got also some strange behavior when using Safari.

What I did was to change collapse settings on "View Issues" page, after that go to page "My View", changed collapse settings of the boxes on this page, went back to "View Issues" page and had wrong collapse settings.

I don't have time at the moment to have a deeper look and can't provide steps to reproduce that work each time I try.

I am not sure if it's WAD that the cookie does not contain the settings of all collapsable sections, but just the one of the latest change, e.g.
MANTIS_collapse_settings |reported:1
after collapsing the "Reported by Me" section on "My View" page and visiting "View Issues" page after that.