Baked Cloth Sim Lost Between Closing and Opening File

Question

I'm running Blender 2.90.1 on a Windows 10 PC. I've created a relatively simple cloth sim of vinyl banners on the side of a tent in a breeze. In order - I've saved my project -> Checked the boxes for Disk Cache and Use Library Path for the Cloth Sim -> Bake. I let it do its thing, save again and see the subfolder with the cached frames for the sim next to the project on my hard drive. All good.

However, after closing and re-opening the project or opening it on another computer (mapped network drives are the same), the bake is gone. The files are still there, and in fact the Cache section of the Physics tab states that "231 frames on disk" but there is clearly no sim happening, either in the render or the preview window. I'm forced to run the sim again each time I open the file which, as one can imagine, is extremely frustrating. Cloth sims don't have the External options to specify a location for the cache like particle or fluid sims do, so that doesn't apply here.

Settings look like this:

And a freshly baked sim SHOULD look like this:

But when reopening the file or on a different system for rendering, despite the sim's Cache settings being untouched, I get this:

What gives? Did I do something wrong or is this a bug perhaps? I suppose the alternative is to bake it in the .blend file but that's not very optimized and can slow things down.

Answer 1

I don't know why that is happening specifically. I found this thread because I was experiencing the same issue, so technically this is not an answer so much as a work-around that will allow you to do what you want.

Check the option to cache the cloth to disk as you have already done, and then bake all dynamics. Immediately after finishing the bake, export the scene as Alembic. This file format will create cached version of fluid simulations and cloth dynamics.

Import that file into a blank blender scene. Select all of your dynamic Objects, then select inverse and delete all the other objects in the scene to leave only the baked dynamic objects and re-export as Alembic again.

Now you can load that Alembic file into your original file and new copies of the dynamic objects will be loaded in with a modifier attached to play the cached dynamics. This is totally stable and will play quickly during scrubbing playing or rendering.

Obviously, you only want to do this after you are happy with the simulation, and you have to go back the to original objects and repeat the process if you need to make a change, but this is a way to get a persistent and reliable cache on disk for cloth and fluid sims.