I initially post about my problem here: https://support.mozilla.org/en-US/questions/1253871 I artificially inflated my requests to match the count I noticed issues at and did not experience the same behavior, but when attempting to archive around 300MB transferred, it fails to export instead returning a download for a 9byte file containing the string 'undefined' rather than the JSON formatted output. I was on a previous build when I first encountered the issue and upgraded to 60.3.0esr (32-bit) and it doesn't seem to be specific to one build.