InvestEngine trades once every business day, you can submit one order per ETF for each trading window. Once you place a Buy/Sell order on a single ETF it will be marked with a clock face symbol and you will need to wait for it to be executed before you can trade that ETF again.
You can still place orders for other ETFs for processing in the same day’s trading window.
But you can’t add a portfolio order to a single-stock order, or place two single-stock orders for the same ETF.
Orders in DIY Portfolios may involve one or all of your ETFs. Orders that involve every ETF in your portfolio (portfolio orders) are Invest, Sell Portfolio and Rebalance Portfolio. To place those orders all other orders in the portfolio need to be executed and settled.
Orders that have not been executed yet are displayed in 'Orders placed' tab. Orders are executed during the daily trading window between 2 pm and 7 pm on business days. You can place your next order after the end of the trading window.
You may have the same ETF in multiple DIY Portfolios, but each portfolio contains a separate holding of shares of that fund. You can therefore place orders on the same ETF in different portfolios.
See also:
How do I cancel or change a DIY order?
My order status displays 'Awaiting settlement', what does that mean for my account?