Hi @RobBarrett,
A fix for this issue is now available in After Effects (Beta) build 24.3.0.037 and later. The I & O hotkeys should move the CTI to the earliest in or latest out point of all selected layers, rather than only the top-most one. If you have a chance, please download the Beta and let us know if the fixed behavior is working for you.
Thanks again for reporting this issue,
- John, After Effects Engineering Team