Did the caching rules/algorithm change for nested timelines?

I'm on 18.1.1.

I have, let's say, a "Main" timeline for the overall project. On that Main timeline are nested my individual scene timelines, so let's call one "Scene". In the Scene timeline is a "Fusion" composition.

Now, it used to be that if I made some changes to the Fusion composition and went back out to my top-level Main timeline, it would have a red line over Scene (uncached), but after I play through it once and give it a chance to render/catch up, the line over it would be blue and it would play smoothly.

Now, however, there's no red/blue line on the Main timeline, no matter how many times I try to play through it, Scene will be jerky until I actually open up Scene by right-clicking Open in Timeline. There I'll see the red/blue line, and once it's all rendered/cached to blue, I can go back out to Main and it will play smoothly.

Is that clear? Have I changed a setting somewhere that affects nested timelines not being rendered until one drops down into them individually?

I'm on 18.1.1. I have, let's say, a "Main" timeline for the overall project. On that Main timeline are nested my individual scene timelines, so let's call one "Scene". In the Scene timeline is a "Fusion" composition.

My guess is that Nested Timelines will not work if there's a lot of complicated shots in the timeline. It will work for "simple" shots. What if you took the Fusion comp and rendered it in place?

In some cases for versioning, we just render out every timeline (to a visually-lossless format like ProRes 444XQ) and then build the project as a series of building blocks into a single timeline -- what we used to call a "Longplay" in the world of linear videotape. This gives us more flexibility with Textless deliveries, different aspect ratios, different sound mixes, and so on.

I kind of don't trust Nested Timelines, but I concede it can be a useful feature under the right conditions.

Depending on what you are trying to do, you can use compound clips on the edit page.

What if you took the Fusion comp and rendered it in place?

It will work to do that — but that still requires having to remember to do it manually at the level of the comp itself or the Scene timeline, or being reminded to do it when playing back the Main timeline and everything starts to sputter.

It's not the end of the world, just one of those "things that used to work" that now, it seems, doesn't.