Blender won't copy pose in dope sheet and mirror paste it So I'm making a walking animation, I got half of the cycle figure out, and just want to mirror the first half to create the second. How ever when I try to copy the third keyframe and flip paste it, I get these stupid glitches. First, when I pressed Ctrl+C it won't copy to buffer. So I have to go into the pose menu to tell it too. Then when I tell it to flip paste, it will only paste the previous pose I copied and flipped. I can't explain it better then that, only if I go back to my last save and start over it happens all over again when I try to copy and flip pose three.
Here is the file, copy the pose at frame thirty, and try to x-flip paste in at frame seventy. If all goes like it does for me, it will glitch.


(Update) So I took one more stab to solve it and I found that if I copied the keyframes I wanted and normal paste them, it worked fine, its only when I x flip paste them that it goes wrong. Another thing that will have when I try to flip paste is it will paste a pose that is not the one I copied and infact don't have any poses like it in key frames
About your copy-paste problem: maybe you've enabled the Copy Attribute addon, which seems to disable the normal copy-paste function in Pose mode and Dopesheet. If you have it enabled, use the copy-paste buttons on the horizontal header.

About your armature: First I personally prefer not to activate the Automatic Keyframe Insertion and the Active Keying buttons because I find it a bit disturbing as it creates keyframes as soon as you move a bone, but it's my own preference and maybe you feel comfortable with them.

Also, when you create key poses (in your case frames 0, 10, 20...) I think it's better to create keyframes for all the bones so you're sure that the flipped pose will be symmetrical and won't depend on what happens in the previous and next keyframes.

Now I think the main problem in your settings is your bone called Root.

First I don't understand the use you make of this bone. The root bone should be the hierarchy top parent, meaning parent of the hip, of the IK controllers, IK pole targets, etc... which is not the case here: You only parented Hips to Root, but what does Roots brings to the Hips function? It's not clear to me... So maybe first fix that.

Once done, most of the time, you won't need to use the root bone, except sometimes when you need to move the whole character.

So, what's exactly the bug that is happening when you copy-flippaste your bones? Actually it flippastes the left bones poses to their symmetrized right copies, and vice versa. But it also symmetrizes the pose of any other bones on their own X axis. That's what happens to Root: As you've created a pose for Root, it symmetrizes it on its X axis, and as its X axis points backward, it's flipped upward, and therefore it moves up Roots and its child Hips and all the Hips children!

So once you'll have changed the Root bone settings, and as you won't have any reason to move it, the problem won't happen any more.