Due to recent changes in the D-Bus API of RHSM (used by the embedded "redhat_subscription" module of the "rhc" role) in EL 10, the "rhc" role registers systems however the content (i.e. the "manage_repos" option in /etc/rhsm/rhsm.conf) is explicitly disabled, leading to no subscription content available in systems.

This D-Bus API change was semi-intentional, due to other changes that were done for the content templates feature of the "rhc" tool (which communicates with subscription-manager using the RHSM D-Bus API).

This was fixed by me recently upstream:
https://github.com/ansible-collections/community.general/pull/9778

Since the "rhel-system-roles" package embeds all the modules needed by the shipped roles (including "rhc"), then this fix must be applied to the embedded "redhat_subscription" module. The fix is present in the "community.general" versions 10.4.0 & 9.5.5.