There are certain scenarios where your limit order may not fill. In particular, with every asset that trades on an open market there is what's known as a bid/ask spread.
Bid/Ask Spread: The price you see on our platform is the last traded price and we use this to help you estimate the price point of your order. In crypto, as it is similar for stocks, there is a “bid price” (which is the best price that you can buy an asset at) and an “ask price” (the best offer for sale). When you try to submit a buy order, your order will be filled at the “ask price” which is the best price available at that moment. This price may be different than the quoted price of the last trade so your order may not fill exactly at what it was quoted for.
Therefore, for example, if an asset has a bid of $0.99 and an ask of $1.01, the quoted price may show the mid-point which is $1.00, however, if you have a limit order set for exactly $1.00, the order will not execute because the lowest price of which someone is willing to sell that asset for is $1.01 (the ask price). In this case there was not enough liquidity available at $1.00 or less for your order to go through.
Please note that all assets, both stocks and crypto, have some sort of a bid/ask spread and this info can be checked at: www.newton.co/prices