FortiAnalyzer support might be able to help you further, as my colleague kbountouris suggested.
However, one other thing you can try is exporting the raw logs (they won't be filtered though, but in csv or txt format if so desired). To export the raw logs, go to Log View > Log Browse in FortiAnalyzer, and select the appropriate device and time period. You shoud see some files ending in tlog; those are traffic (and UTM) logs received by FortiAnalyzer for that FortiGate in that time period. You can download the files from here in csv or txt format. You can also download in native format, but that isn't really human-readable. Do note that the downloaded logs will be ALL traffic and UTM logs written by that FortiGate in that time period; there is no way to filter when downloading from here.
+++ Divide by Cucumber Error. Please Reinstall Universe and Reboot +++
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