This happens because when navigating to the cache, the map is zoomed in too far and there are not tiles available for that zoom level. Zoom about a bit to load those tiles. In our 2.0 version this will no longer be an issue.
This shouldn't happen, and I am not able to reproduce. Are you saying that Cachly opens back up to the same offline list as before and then shows the message? Or, after a while iOS has killed Cachly, and you have to reopen it (showing the startup splash screen) and then it shows the error?