I never use a brush, i use a really soft sponge, otherwise i could scratch the leather. And than I just let my balm sit until the leather absorbed it.
Try it again but without wiping it off. Just apply a really thin coating and wait until it disappears by itself. Usually overnight And as I said earlier, I don't use just the oil. Because just oil is less practical to work with as it does not stcik to the leather. So whilst my leather balm is mainly jojoba oil, when applied it will stay on the seat til the leather basically sucked it up. And Saab in general has relatively thick and a bit firm leather. Also, maybe something was spilled on your seat and dryed up and now it has a coke coating or something on it I dunno.
I use something similar to this:https://www.amazon.com/-/de/dp/B01LFMGFGY/ref=sr_1_5?__mk_de_DE=ÅMÅŽÕÑ&dchild=1&keywords=leather%2Bbalm&qid=1599076478&sr=8-5&th=1
Seems like the only type of the "german" leather balm avaiable in the US. Although mine has different ingredients.