No additional license is required for FortiView. You might want to confirm that the FortiAnalyzer is receiving logs. Check "Log Browse" for new logs. Once the logs are received, they will be inserted into the SQL database (thereby generating "analytic" logs). It is analytic logs which are displayed in Lop View & FortiView.
You mention that there is enough space -- also make sure the minimum requirements in terms of memory & CPU count have been allocated to the VM.
FMG-08 # execute sql-local rebuild-db Rebuild the entire log SQL database has been requested.This operation will remove the log SQL database and rebuild from log data.This operation will reboot the device.Do you want to continue? (y/n)
be very careful and make sure you create a proper back up of your config, DB and logs. Even create a snapshot of your VM too. and then rebuild the DB.
I would say create a ticket with the FAZ team to investigate the issue.