Hi @Leboy83, welcome to the community!

Here’s the Status page where you can check to see if there’s any known issue happening with Klaviyo. https://status.klaviyo.com/

Right now, all is fully operational. I’d encourage you to use Chrome if you’re not already - that’s the browser Klaviyo works best in. Otherwise, try logging out and logging back in. Depending on the length of your session, you might be experiencing that issue because you’re about to be automatically logged out of Klaviyo.  I’ve had this happen before when scheduling campaign emails. 

Warmly,

Gabrielle

Klaviyo Champion & Marketing Lead at ebusiness pros