Export of identity environment results in empty output file.
IM 14.5
Timeout in browser or terminal session (if export is via importExportUtility) due to the fact that the environment is big or performance of the system is slow.
Use tmux session. It will allow enough time to export all file.
See also Unable to export IME using the IM Management Console (blank screen when trying to export) logs stop processing messages with no error present for a similar problem but other causes.