I could swear that this was working as recently as a week or two ago, but I am unable to copy/paste keyframes in the Animation window. I've tried clicking individual keyframes (so they turn blue), pressing ctrl-C, then moving somewhere else in the timeline and pressing ctrl-V. I've made sure the scrubber was on a position with a keyframe under it. I've tried using "Copy" from the edit menu, I've tried Duplicating, and nothing seems to work. Did I just imagine that this was a feature?
This is getting bizarre. Yesterday copy/paste was working for me again: just highlight a keyframe (blue), ctrl-c, move to another position in the timeline, and ctrl-v to paste. Now today it's not working again. Does anyone else experience this? Is there some subtle condition I'm not aware of that prevents copy/paste from working?
or is that some read-only animation issue? (imported animation, vs. copied version of it, or one animated in unity)
I'll report a bug. I was just hoping I was doing something wrong that someone would identify as a reason for the inconsistent behavior. It's currently letting me copy/paste again. This is the same animation I've been working on throughout, and I can otherwise edit the animation. It's just that copy/paste sometimes isn't working.
I don't know if you still have the same problem. Well, actually I had the same problem today using the latest version and it was sorted out just by restarting the editor.
[Workaround] click the animation area where the keyframes are displayed before pasting. I have a similar problem in 2020.1.6f1. While I am able to copy/paste keyframes within an animation, I cannot copy keyframes from one animation and paste them in another. I am 99% sure that this was working in Unity 2019. When I copy keyframes and I switch to another animation and back again, I cannot paste. It seems that changing the animation clears the copy cache. This is really unfortunate. [Edit] I am now 100% certain that this works in Unity 2019.
Since I do not seem to be alone with this, I sent a bug ticket. Usually, the Unity support is quite responsive so we should have an answer to this shortly. Might be a duplicate with the one that @dgoyette reported, but my ticket is specifically about copying between different animation clips.
Got an answer, it's a known bug https://issuetracker.unity3d.com/issues/keyframes-are-not-pasted-from-one-animation-clip-to-another and the workaround is to click into the animation area (where the keyframes are displayed) and then you can paste keyframes just fine.
Same problem here in 2020.1.4f1. What works for me is to use the top menu Edit>Paste instead of hotkeys. It seems is the key bindings are messed up but it works from the menu just fine. when you open the Edit menu you can see that there is no hotkey assigned to it. I have just checked. The hotkey is not assigned. 1. Go to Edit>Shortcuts... 2. In the search field type in: "paste" and press Enter. 3. The first command in the list below (Main Menu/Edit/Paste) has no hotkey assigned. 4. Mouse click on the field next to it, press Ctrl +V and Enter. 5. Done.