[Walter Soyka]

Make sure you enable the frame blending switch for the footage layer inside the precomp’s timeline.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

You can use the new pointOnPath() property to get the position values you’re looking for.

Here’s an example:

13633_followthepath.aep.zip

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

This expression will do what you want. Use it on the time-remapping property, and ask me questions about whatever isn’t clear:

var startFrame = 15;
var endFrame = 35;
framesToTime((timeToFrames(time) % (endFrame - startFrame + 1)) + startFrame);

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Have you customized your presets at all, or were you working with any third-party encoders?

Is there anything interesting in AME’s output log?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

You want to use a layer map to drive the scale of the particles. See this for how to use layer maps (just be sure to use Scale instead of Displacement as in this example):
https://www.redgiant.com/tutorial/07-getting-started-with-trapcode-form-layer-maps/

And here’s the tutorial on how to set up custom particles:
https://www.redgiant.com/tutorial/04-getting-started-with-trapcode-form-custom-particles/

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Is this from a custom output module template? Maybe you could try re-creating the output module from scratch and see if you get the same error.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Use Time Remapping [link] on your precomp layer, set the two keyframes you wish, then use loopOut() as you normally would.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Here are a few light tips:

I generally work in 32bpc mode for big fat lighting effects. This setting is fundamentally different than 8bpc/16bpc in how extreme lighting values are processed. Instead of clipping at white (or black), you push well beyond maximum brightness and later recover that detail with additional effects. Once you do this, you can split a lot of light generation across multiple layers, combine them with Add blend modes, and then pull them back down with shadows or Exposure effects on top. See here for more:
https://helpx.adobe.com/after-effects/using/color-basics.html#color_depth_and_high_dynamic_range_color

Trapcode Shine is perfect for those cast light rays:
https://www.redgiant.com/products/trapcode-shine/

You can get a lot of mileage out of a lens flare plugin (like Video Copilot’s Optical Flares) for generating light sources. For the style you’re showing here, I’d recommend turning off a lot of the lens elements.
https://www.videocopilot.net/products/opticalflares/

Lastly, consider third-party replacements for Ae’s default Glow effect (which I personally find difficult to use with good results):
https://aescripts.com/deep-glow/
https://www.redgiant.com/user-guide/universe/glow/
https://borisfx.com/support/documentation/sapphire/ae/glow/

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Does it do this in new projects, too, or only in the current project you’re working on?

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Walter Soyka]

Glad to hear you’ve worked through your challenge, Adam! Good luck with your project.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive   |   RenderBreak [blog]   |   Profile [LinkedIn]