Despite what Tim and the PR department says, FAB sales have pretty much crashed for most sellers. Pixiebell has already talked about the reasons, people just have a terrible experience with FAB and worse yet, those who try to buy assets are often prevented from it because of bugs.
Making matters even worse yet, newer sellers are immensely disadvantaged, as it’s near impossible now to find good, new assets because of the awful UI (e.g. search and categories), how their assets get drowned out by the flood of AI generated assets, how there is no favorite function anymore and how the arbitrary 5-star review system disadvantages new sellers.
So it’s really not your fault you are not making sales, although txbm is right in his advice to make these models available in the UE (and perhaps unity) format would perhaps help a bit.
You can also advertise your models, with a link to your store page, on Reddit gamedev / 3D subs and build yourself a profile on Bluesky. Just don’t expect it to change a lot until you build a large enough group of fans.
If I may give you another advice, the topology of your models could be improved. Looking at your " Medieval Building Pack" I see a lot of unnecessary polys / faces that don’t need to be there.
I made a quick screenshot and painted over the areas as an example that can be completely removed and made into a single face.
This is important for gamedevs, who need to keep the polycount of their maps / scenes in mind. So less is always better.