Tested on Live
As well as on a fully updated installation (performed yesterday with an everything netinstall).
Going to network configuration, any performed configuration can't be applyed because the "Apply" button stays gray and can't be pressed.
FWIW nmcli works
Created attachment 1613604 [details]
I can confirm this, Apply button is grayed out and can't be used. It only affects the wired network configuration, wifi configs can be adjusted normally. Tested bare metal and a VM.
Proposing as a blocker due to:
"All elements of the default panel (or equivalent) configuration in all release-blocking desktops must function correctly in typical use. "
This needs to be reported upstream.
I usually have the approach of reporting things to RH Bugzilla if I need to mark it as a blocker, and if it gets accepted, we need to contact the developers anyway, so they'll know (and having extra tickets is just needless work). If it is not accepted as a blocker, then it makes sense to forward the ticket to upstream, so that this gets fixed long-term.
Discussed during the 2019-09-16 blocker review meeting: 
The decision to classify this bug as an "AcceptedBlocker" was made as it violates the following criterion:
"All elements of the default panel (or equivalent) configuration in all release-blocking desktops must function correctly in typical use"
Upstream bug report is https://gitlab.gnome.org/GNOME/gnome-control-center/issues/677
FEDORA-2019-b5fa4a709a has been submitted as an update to Fedora 31. https://bodhi.fedoraproject.org/updates/FEDORA-2019-b5fa4a709a
gnome-control-center-220.127.116.11-3.fc31 has been pushed to the Fedora 31 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2019-b5fa4a709a
It works. Thanks.
gnome-control-center-18.104.22.168-3.fc31 has been pushed to the Fedora 31 stable repository. If problems still persist, please make note of it in this bug report.