Data download from Horizon Analytics reports is apparently limited to 100000 records (lines) and according to documentation, export to S3 via Rules Engine should be used when more records need to be exported. This makes it really hard for end-users without Rules Engine access to export large dataset (e.g., usage data) from reports to do further analysis.
The option to export to csv (via an email link when the file was ready) available on the old reports was great for these purposes. I'd be very happy to see this option (or another way to easily download larger datasets) return.