Many are probably have a "Free" viewing, so they get scraped by the system, but anything added to the post like a video or image, is probably locked behind a paywall.
I already tried importing myself, and it doesn't import free view content.
You need to import something behind a paywall for the system to even accept it.
A lot of people who use fansly adopted the "pay for the option to pay for things" approach
We've got Sif Avellana memes here and yet still no Fansly imports of her stuff, how unfortunate.
It's problems with the importer it seems like really, it doesn't accept free content and the fact I can barely find any Fansly stuff at all scares me off trying to import paid content to even see what happens, like how Kemono had the issue that killed Fantia imports with getting accounts banned months ago, which are still dead in terms of updates with fixing imports there even now.