The 4.3 console available channel list is missing candidate-4.3. https://github.com/openshift/console/blob/4aa613e9c1fc84e4fec707f295f9113367708c8c/frontend/public/module/k8s/cluster-settings.ts#L30-L33
Now the available channel are candidate-4.3, stable-4.3, fast-4.3 on console . 4.3.0-0.nightly-2020-02-05-220314
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2020:0492