We've noticed that thumbnails of images in a service are not necessarily saved when a service is edited on a different computer.
For example, I created a service in V 3.1.2 that has a single image as the first service item and saved it in DropBox.
I then opened that service on a test computer that has V 3.1.6 and everything looked good.
I changed one item (made one service item loop) and saved it back to DropBox.
Then opened the service on my original computer (V 3.1.2) and got a "corrupt file" error.
On inspecting the original and "corrupt" service files, the only difference is that the "corrupt" file, edited on the other computer is missing the thumbnails folder. The actual image is there.
If I move that image file to the end of the service, and repeat the exercise, I still get the "corrupt file" message, but only after the items before that image are loaded perfectly. I would have expected OpenLP to create any missing thumbnails on the fly.
Normally, this is not a problem for us and we typically have the service created by one of us at home and then show it at the church. On occasion, however, we may have two of us preparing the service and we run into this problem.