Can't paste position Key Frames in AfterEffects

For a while now I've been having the issue that whenever I Copy a position keyframe(s) from one layer and Paste it onto another, AfterEffects won't register the Paste. If I Paste it onto the layer with the Transform menu closed, a round dot will appear on the timeline, indicating that the keyframe has been Pasted onto the layer. However, when I open the Transform menu the keyframe isn't there and the dot disappears. If I Paste it onto the layer with the Transform menu open, AfterEffects doesn't acknowledge the Paste, and weirder still the Scale and Rotation options in the Transform menu will highlight as if they've been selected. 

I've been having this issue for a good year or two now. My AfterEffects is fully up to date and I've uninstalled and reinstalled several times, but the problem persists. No matter what I do I can't fix it and I can't find anything online about this specific problem.

Does anyone know what's happening? I'm not hugely savvy with AfterEffects and I'm hoping I'm doing something wrong or have a setting applied that is causing the issue. 

Thank you all in advance for your help.