Apologies for the late reply — I overlooked your message, sorry about that.
A few things to try:
First, restart the app on your phone. The file sometimes takes a little while to appear, so a restart often does the trick.
When a session first arrives, it lands in your local sessions rather than directly in the logbook. You can spot these by a double-arrow icon with a red number next to the “Logbook” title. Tap that, and you can transfer the session into your logbook from there.
Normally sessions are moved into the logbook automatically, but if something interrupted the process — for example, no internet connection at the time — they stay in the local list and need to be transferred manually.