There is a post for Aug '19 on this subject (SNAPSHOT When I use the <<SNAPSHOT(LINKTOVIE...). It suggests SNAPSHOT() might still be in beta and not support the following usage:
The LINKTOFILTEREDVIEW() call works as a standalone Action inside the same App. However, when inside a SNAPSHOT() call contained in a Google Doc template … used to create a PDF file …only a grey box is created.
Is this still the expected behaviour? Is there a work around within AppSheet to render a filtered view?