So I tried firing up a new project in 4.8.3 and injecting the most recently released content - it didn’t ask me to select a version to inject and pretty much just worked and included all the latest updates. Are you able to reproduce the error still? If so, what was it?
I may try downloading say 4.6 again later and try to inject the assets into that version and see what happens. I expect it’ll break but it’ll answer a few questions about the marketplace release process. Thanks for raising this!
Edit
I can confirm that using it with 4.6.1 is totally broken and almost immediately crashes the editor. Epic HAVE converted the latest asset so that it will open in 4.6.1 without any warnings, but clearly it doesn’t work in that version at all. This means you probably can’t trust any older version to work as it did when the cel shader was released for that version.
For now most people should be able to assume that 4.8.3 works best and 4.9 is also fine (make sure you select the 4.8 version when adding the asset in order to proceed though).