Looking for answer I came across @Unx question without solution. But gave it a go in few other combinations. Whether Syncthing has changed options since then or not, below ignore will work at removing Android folders from synchronizing without any errors.
I don’t know which old question you are referring to, but ignores only make problems, if you have at least one “unignore” (!) set. As this means, we need to check every folder to see if the is an unignored file/folder somewhere inside.
