When I search for this setting in Sync it shows up.

But when I click on it it goes to a page that does not offer the setting either at the top level or buried inside of anything else.

When I go to look for this setting again in my home instance, I find that it is in fact now correctly set. It was not correctly set when I posted. So my fix stuck.

I assume, as someone else suggested, that there's some caching going on somewhere, either on the transmitting end or the receiving end.

That's fair: as far as Lemmy knows it was posted by a self-declared bot, even if that puppet later became a real boy.