I have a strange problem with magento 2 and one of the good selling themes in themeforest. The problem is not present with default magento 2 theme.
When I am signed in to the store, it still shows me sign in button instead of sign out button. When I clear the magento 2 full page cache, the problem dissapears, but when I open the page from another browser with not signed in user and refresh the page on signed in browser it appears again.
After several days of investigation I have found that the problem is caused by cloudflare, which I use also to manage that domain.
Turning on and off any feature in cloudflare panel didn’t help. The only solution was to bypass cloudflare from domain register.
I have tried different page rules, bypassing caching, security… and none of them helped.
What could cause that issue, because I want to use cloudflare in front of my store.