>It thus returns html response back but does not clear session.
Could you please elaborate? Why do you think it doesn't?
Please generate HAR file containing **full** flow you have issues with. Here is some clues how to do it: [link](https://support.cloudflare.com/hc/en-us/articles/203118044-How-do-I-generate-a-HAR-file-) (Please use Firefox for this, Chrome generates incomplete HARs). Don't forget to set "Persist logs" checkbox, otherwise only the last page's trafic will be captured.