The single most important piece of information when reporting an issue for investigation is the problematic session's ID. This identifier is shown right after the "&token=..." URL parameter of the browser during the problematic session:
If at all possible, several problematic session IDs are better than one.
A screenshot of the entire session screen that shows the problem, can be even more helpful than just the token identifier. That's because it:
It helps knowing whether your issue is entirely repeatable / consistent, or whether it happens only sometimes.