Oh yeah, that’s an old bug! Fixed long ago.
From Browsertrix? As I mentioned, downloading larger files in a web browser can have issues… If your connection drops out, web browsers aren’t great at resuming. You may consider downloading the individual ~10GB WACZ files available in the files tab of your archived item. Granted, the process for loading these into ReplayWeb.page via a JSON file is a little under-documented right now.