[9.4.0rc] Pamac stuck at "Preparing..." when initiating install or upgrade

Issue: The title sums it up.

I noticed this issue in these two cases:

1. Pamac 9.4.0rc (from pamac-X 9.4.0rc-5), with the GTK interface, on Manjaro KDE, in a VirtualBox VM, no Flatpak support enabled, when I wanted to do a system upgrade.

2. Pamac 9.4.0rc (from pamac-X 9.4.0rc-6), with the GTK interface, on Manjaro GNOME, in a QEMU-KVM VM (with Virtual Machine Manager), with Flatpak support, when I wanted to install Inkscape from repos.

I am not the only one having a similar issue. On the forum:

https://forum.manjaro.org/t/testing-update-2020-03-07-kde-git-pamac-9-4-haskell-python/128084/8?u=frog