Keyframe properties change after moving playhead

Question

I'm attempting to animate someone passing off a ticket to another person, and decided to use the "child of" object constraint for the ticket to attach to both rigs (created using rigify). I've keyframed these appropriately, but when adjusting the location offset, I've found that the location, when keyframed, changes despite nothing interfering with it or me changing the keyframe.

When setting keyframe:

After moving playhead off keyframe and back onto the same keyframe:

Note: this is the same keyframe, and no actions or other keyframes are overlapping.

Answer 1

I believe I have done something wrong with my keying set, as removing all influence of the "child of" constraints (after positioning it) and then keying it seems to work fine.

I'll post when I have found a proper answer that doesn't obstruct workflow, but for now it seems to work fine.

In the meantime, any help would be appreciated.