Dragonfly 5 Pro sonar log file problem

My DF5Pro is configured to save sonar logs (set to ON in chart options). But when I log into my Navionics acct to upload sonar logs, only the last hour or so of the last trip is actually uploaded. I typically fish for 4-6 hrs per trip, and only upload to Navionics once or twice per month. So what is happening to the other 40+ hrs of sonar logs?

In trying to troubleshoot this problem I looked at the files on the bundled Navionics+ chip. But I don't know what files are supposed to be there so it's hard to know if I am missing something. Can you provide some guidance on why my DF5PRO is not logging or uploading bathymetric data properly?

Thanks

Jim