Execution speed/OTC execution

I have been with trading212 for about 1 year. I trade only US listed stocks, sometimes I buy microcap stocks. Oftentimes, I place an order right at the ask(I got another broker that provides L2 for bid/ask), but it wont execute, or it takes minutes to execute. I took at least 100 trades in the past year, and every single one has been cleared OTC. Is there a minimum capital requirement for an order to be routed to the exchange dircetly? As soon as the stock gets volume/becomes liquid it is not a problem to sell my shares, but as long as its illiquid it hardly fills any orders even if they are placed above the current ask. A recent example of this occurred on 08.09, when I set a limit order above the ask, but it took 7 Minutes to fill(OTC).
I would be happy about an answer, as I enjoy everything else trading 212 offers, except the execution mechanism.
Kind Regards.

When you place a limit order, it can sometimes only get filled partly at first if there aren’t enough shares available at your price. The rest of the order just stays open until it can be matched at your price (or better). This usually happens with microcap or less liquid stocks.

There’s no minimum capital requirement for orders to go directly to the exchange. Sometimes trades get routed OTC (over-the-counter) instead, if that gives a better outcome than going straight to venues. Our smart system automatically manages the routing by evaluating various options and directing the order to where it can receive the best execution.