Q:

Keyframes won't respond to 'Cycles' f-curve modifier

I'm making some material tests with Mapping nodes, but the Y scale of one of the Mapping nodes won't respond to the Cycles modifier. The other values do respond to modifiers but these won't:

I'm not really use why this is happening, perhaps it's an easy fix and I don't know about it.

A:

The Cycles f-curve modifier is working, but you have a keyframe on frame 4335 which is being included in the modifier. This means any repetitions of those keyframes are happening after frame 4335. If you zoom very far out after adding the modifier you can see that.
I presume you actually want that keyframe to be on frame 105 as that causes creates the same repeating pattern as the X Scale channel.

