Hi @_jm
I also had the issue and reported it here Cannot give Progress initial look of value=0, max=100 · Issue #2080 · holoviz/panel (github.com) with a workaround.
A fix has been implemented here and is already merged to the master branch. It will be in the next release Add empty progress bar by Hoxbro · Pull Request #2088 · holoviz/panel (github.com)