I have the same issue for software-properties-gtk. Software-properties-qt does start, but doesn't show any software sources as enabled.
If I had to guess, I'd blame the fact that upgrading to 24.04 seems to have moved default repos from /etc/apt/sources.list to /etc/apt/sources.list.d/ubuntu.sources and changed the format to the one specified in deb822. Attached here is my /etc/apt/sources.list.d/ubuntu.sources
I have the same issue for software- properties- gtk. Software- properties- qt does start, but doesn't show any software sources as enabled.
If I had to guess, I'd blame the fact that upgrading to 24.04 seems to have moved default repos from /etc/apt/ sources. list to /etc/apt/ sources. list.d/ ubuntu. sources and changed the format to the one specified in deb822. Attached here is my /etc/apt/ sources. list.d/ ubuntu. sources
upd: found this change that probably caused this bug: https:/ /discourse. ubuntu. com/t/spec- apt-deb822- sources- by-default/ 29333