Not loading OctoPi

What is the problem?
When connecting to my pi for the second time it will only show a page like you are not logged in.
Reload and re logging in will not resolve it.
But flushing the cache will. Because when i do ctrl+F5 the page reloads and i get loaded in and be able to control the printer.

edit
I found that octoprint now runs better in Chrome than in FireFox.
I used to use FireFox to connect to OctoPrint. But the video stream is choppy and freezes. And Not in Chrome. But both browser display the same problem with login and have to do ctrl+F5.
I must say OctoPrint resolves better in Chrome at the moment.
/edit

I'm using a Rpi 3 with OctoPrint 1.3.10 running on OctoPi 0.16.0
And the pre heat and Themeify plugin.

Did anyone else also ran in to this problem?

And if so did you find a solution?

What did you already try to solve it?

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)

You might visit the repository's Issues page, search for Firefox and see if there's anything which might affect you.