After copying multiple keyframes, it's impossible to add multiple keyframes

Repro:
1. Add a couple of keyframes. Select a column of keyframes (using the top keyframe) copy and paste (just copying is enough to trigger the bug)
2. Move the red time gizmo and try to add the keys for all properties by pressing the add keyframe button - it's impossible to add the frames

It is possible to add single keyframes and so there is a workaround. After adding a single keyframe you can add keyframes for all properties again.