Nuget package source is unchecked automatically

Question

I have added our org specific nuget package sources that has urls pointing to our local network for which I have complete access. After adding it by checking the checkbox in the package manager settings and closing the window, when I check the list of package sources again, one specific package source is getting removed ("unchecked") automatically. Either visualstudio or nuget extension removes the source. The same source was working sometime back. Not sure if it has anything to do with VS/OS updates. At the same time, other custom package sources are working and other team members are not facing this issue.

Answer 1

Jack's answer did not fix my issue. I ended up having to delete my private nuget store, and recreate it with a different name. somehow that fixed it. I checked all locations a NuGet.Config file could be stored, and didn't find a single reference to disabledPackageSources.

I hope my workaround helps someone else avoid the hours of lost time.