UPDATE: The solution seem to be to reproduce CefSettings values in CefRequestContextSettings when creating CefRequestContext that is passed to CefCreateBrowserSync. CefRequestContextSettings include values such as cache_path, ignore_certificate_errors, etc.

The cache_path directory is not initialized properly, only two files are created in that directory, while in cefclient/cefsimple there are many more files/dirs in it. There are no warning/error messages in console or the debug.log file, so no hint on what went wrong. This causes cookies and indexed DB not to persist between application launches. Tested with CEF Python v55.2 on Ubuntu 14. Tested by user with v53, v54 and v55, all reproduce the same issue.

Reported problem with more details on the CEF Forum:
https://magpcss.org/ceforum/viewtopic.php?f=6&t=14763

User report about the problem on the CEF Python Forum:
https://groups.google.com/d/topic/cefpython/sXwC_NIKjvk/discussion