Advanced and intuitive keyframe animations for Virt-A-Mate - acidbubbles/vam-timeline
github.com
For your situation, you need to use the keyframe pose command to assign your current pose to the current keyframes (more tab -> advanced keyframe tools -> keyframe pose).
Also be sure that there isn't some other animation running on another layer. When that happens, edits will be ignored (press STOP several times before editing).