GSAP 3.5.1 ( latest version ) is now included in Storyline 360

Hi D R,

For sure possible. Let me first explain what is causing the glitch in your animation.
For a seamless loop, start and end need to be exactly the same. As you end differently then you begin...a glitch will always be visible. So you need to end it exactly the same or change the beginning so it will fit.

Using a Storyline layer,timeline and cuepoints also makes it harder then needed. You can as easily use GSAPs buildin timelines to do this. 

So lets see how to get this done perfectly.

Approach 1:
Using your Storyline i changed the jump at the end of the layer to go to cuepoint #1.
Prolonged the timeline on the layer a bit, so you see it happening better...
And added a cuepoint where the animation is set to 12 degrees.

As you can see when publishing, there is still a glitch when looping. I do think this is SlideLayer and Cuepoint related as Storyline is not precise enough to get this working perfectly.

Approach 2:
Jumping back to 0 is often better for Storyline timelines. And setting the green Blooddrip to 0 at cuepoint 5 shows that the loop now is seamless. But we want it to loop at 12 degrees.. How to do that ? 

Approach 3:
Tried to add a Boolean variable (True/False) that will be set to True when the SlideLayers timeline ends...and then at start sets the drip to 12 degrees. At first this failed too... so i changed the trigger you had jumping back on the timeline into 2 triggers...hiding and showing the timeline at the end. This worked well and now it is looping nicely. This fix might work on your original too.

Approach 4:
Using GSAP's timeline to control all. As you can see here...this is really powerfull and easy.. Using yoyo to go back and forth.

Here you can see all approaches and the Storyline changed is attached.
https://360.articulate.com/review/content/b276fadf-093d-4578-8f3f-95daa2d47a41/review

Do hope this helps you to continue your yourney :-)