Dropbox sync and .odt changes not showing

Greetings! Dropbox and Collabora on my Chromebook synced perfectly when I downloaded them yesterday. Changes I made to .odt documents were showing, so I was I pretty happy. This morning, I noticed that not all documents had synced any text changes. This morning, I can open my Dropbox .odt docs with Collabora but none of the changes I make are saved. Any ideas on troubleshoooting? Thanks.