Hi! Getting a little frustrated here, hoping for a solid explaination or best practice.
EDITED 4.25.2020*****    https://youtu.be/05d01pBx74A     **********
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^example youtube video
I have been animating with iClone since about 2015 to create animation loops for 2D fighting games. 
This issue I am about to explain has come and gone and I don't understand why some updates I have this issues and then other updates the problem is gone. 

Current Version: iClone 7.72.3818.1 

PROCESS:
I import my custom character that uses the iClone standard animation rig ( iAvatar or CC3 Character Creator file directly exported to iC7)
I select the character and press 'N' to dial up 'Edit Motion Layer'.
I left click the LOCK icons adjacent to the feet (ankles?) 
After turning the LOCKs on, I click on the 'hip bone' and I either do a soft rotation (press E) or move hip position on z,x,y axis (press 'W')
Using the options listed above I make very soft movement adjustments to hip rotation and hip's Z position to create an animation loop (Think standing Idle stance)

PROBLEM:
The feet on the animation loop slide around instead of staying stationary. 
This has come and gone with different updates in iClone 6 or 7 and I would love to know why and how I can end this problem. My process hasn't changed but something has in the appliaction

Thanks!!!
Ps: Perfect world, it would be great if we could dial into the actual x,y,z, coordinates via the UI and just copy the position of said bone and apply it to desired frames.
If I am an idiot and have missed a glaring option, please, call me out!

Hi

The feet are locked as default if you click them you will unlock them.
You can get the x y z bone co-ordinates in the edit motion layer by selecting the FK Mode and selecting one of the bones.

Chris.

Thanks Chris - I don't think you understood exactly what is happening.

Even with the lock enabled the problem is persistent - the application slides the feet around in the filler between key frames, I will upload it on video to demo.

When you first open the Edit Motion Layer panel, the feet are locked by default. Notice the T and R indicators in the dots, and also that the little locks for the feet are closed. So if clicked them thinking you were locking them, you were actually unlocking them. See here:
https://manual.reallusion.com/iClone_7/ENU/Content/iClone_7/Pro_7.4/08_Animation/Motion_Layer/Introducing_the_Edit_Motion_Layer_Panel.htm?Highlight=edit%20motion%20layer

Here's the video


https://youtu.be/05d01pBx74A

just replying to your comment to be sure you get a notification. I added a video of the issue I am having. Thanks for taking the time to help!

https://youtu.be/05d01pBx74A

just replying to your comment to be sure you get a notification. I added a video of the issue I am having. Thanks for taking the time to help!

https://youtu.be/05d01pBx74A

When this issue becomes overly annoying and well over the level I can tolerate, I use Reach Effectors to animate feet.
Animate all bones normally, but if you need to move/rotate feet, animate those reach effector balls.
Inconvenient and annoying - yes, but gets the job done.

Thanks for the link!