Upfront Editor page does not save and images don't load.

I keep getting the Another Tab is already working on this". And updating page and image insertion is taking a long time.
I have tried this
https://premium.wpmudev.org/forums/topic/another-tab-is-already-working-on-this-error-message#post-1278792
and checked and logged out of everywhere. Reset user password and also Reset Reset Upfront Cache but nothing works. Reseting Upfront Cache removed the Another Tab is already open message. But when I try to update a page it takes a very long time to update and also when I try to upload image it never ends the image insertion.
The issue is appearing only for only one page. While tested on other page it works fine.