New(ish) seller, cannot win the buy box, and no sales.

I’ve had a sellers account for years and sold items 6 years ago. I’m now back after having bought 1000’s of products from a closing company.

Problem I am facing is Amazon doesn’t trust me to put me on my buy box, despite winning “Featured offer” and having the lowest price on every single product I am listing with free delivery.

How long does it take to start getting sales so Amazon trust me enough to allow me to compete for the buy box? Also, There’s products where currently no one else is selling it apart from myself, yet on those products, I don’t show up at all and the product just looks out of stock.

Kind of a catch 22 position where I’m sitting on £30,000+ worth of stock that I cannot shift at all.