Beware of Order Routing on these New "App" Brokerages

I have an account with a traditional brokerage that lets me see the market depth and lets me specify what exchanges to place my order on. When I place my order, I see it post directly on the exchange. I use a strange number of shares so I know that order is mine. When the price moves in my direction and my bid goes to the front of the line, it soon executes.

I recently signed up for a promo on one of these "app" brokerages, one of the many that popped up in the last few years targeting young people and their smartdumbphones. I went through all the settings and found nowhere to specify order routing and nowhere to see market depth. I placed a buy order with a strange number of shares and went back to my tradititional brokerage to see if the order shows up in the bid/ask depth. Nothing. I see the bid move to my order price, and even below it, yet no execution. Nothing. Eventually the price moves back up away from my order and it didn't execute.

I've done this experiment multiple times, and my traditional brokerage always gives me better execution, according to the actual market, and sometimes even gives me better-than-spread priced executions. I've gotten sell orders executed above the entire day's range and buy orders executed below the entire day's range.

In the "app" brokerages, the orders won't execute unless the price moves past the order price definitively, and even then, who knows. I once placed an order at night for the the next day. The next day, it never executed, despite the order price being within the day's price range.