I have been trying to animate the common rat.
https://marketplace.reallusion.com/common-rat

But the problem I am finding is the walk cycles are stationary, like the old style walk cycles, and as such there is massive amounts of foot slide and none of the tools for correcting this (the foot print tool thing) are available to me. How do I judge how far the rat needs to go in order to show the walk without a foot slide, and if this is impossible to guess, how can I cure the foot slide.

Another weird thing is the move (from start point to end point) doesn't seem to happen straight away, and there are about 30 frames (from 60 per second), where the rat just doesn't move.
Below is a short video, first on play, then on scrub. Any one who has any ideas or pointers, please let me know. Or am I just barking up the wrong tree here, animation wise.

https://imgur.com/mMPB0tO

Not much can be done with rootless motions other than tweak root transform until you get an optimal motion without much sliding.
Once you add transform key at the end of the loop (make move only for a single loop), switch it to linear in transition curve presets to avoid idle at the beginning.
After you set an optimal loop transform, select collect clip precisely to the motion loop length and add to perform.
Run perform and extend the loop for a much as you need.

I think I understand.
By 'tweak root transform' for optimal motion without too much sliding, do you mean, the transform gizmo that I use to move the rat? So basically, find how far it needs to go to reduce sliding? Is that what you mean?

I looked at the transition curve pre-sets, but I couldn't see a way to edit them for the start or end of a clip. Where should I be clicking to do this?

I did understand about collecting then motion and adding to perform. That's a brilliant suggestion.

By 'tweak root transform' for optimal motion without too much sliding, do you mean, the transform gizmo that I use to move the rat? So basically, find how far it needs to go to reduce sliding? Is that what you mean?

That's correct. You only make one Transform key precisely at the end of the loop frame.

I looked at the transition curve pre-sets, but I couldn't see a way to edit them for the start or end of a clip. Where should I be clicking to do this?

You set Linear preset to that Transform key you create at the end of the loop, because that is what moving it across.

Ah I see. I was right clicking inside the clip, rather than on the actual keyframe.
Okay, that sounds straightforward. I can try to create a motion in a blank project, that doesn't have foot sliding, adjust the curves on either end of the transform, then collect that and save it as a new motion in the perform.
Never done any of that, but I guess there is stuff in the manual on how to get it done :)
I'll post back when I have something worked out.