Progress bar stalls for file backend

I have:

([x] when completed)
searched https://gitlab.com/duplicity/duplicity/-/issues for similar issues. If you find a similar issue and the issue is still open, add a comment to the existing issue instead of opening a new one. If you find a Closed issue that seems like it is the same thing that you're experiencing, open a new issue and include a link to the original issue in the body of your new one.
searched https://bugs.launchpad.net/duplicity for similar issues. If you find a similar issue, open a new issue on here and include a link to the original issue in the body of your new one.
tested that this issue still occurs on the latest stable snap (install instructions: https://snapcraft.io/duplicity), please include the snap version (snap info duplicity | grep installed) output: installed: x.xx.xx (xx)
ideally, tested that this issue still occurs on the latest edge snap, if you can test without risking your data. Please include the snap version output: installed: x.xx.xx (xx)

When running duplicity with the --progress option, progress stalls at 0% and does not move, although files continue being copied.

Tested with snap versions 0.8.17 and 0.8.19.dev53.

Related gitlab bug: #19 (closed)

Run duplicity with the --progress flag and the file:// backend.

Progress stalls at 0%

Progress updates as files are copied.

Example line:

0.0KB 00:00:12 [0.0B/s] [>                                        ] 0% ETA Stalled!