open the trading widget. switch to limit. type in number of coins desired. then click the market order tab. than notice you cannot buy your market order because the button is grayed out. steps to reproduce included as images.
Also guys compare market buy vs market sell tab - the UI doens't look the same - missing % buttons!
Sorry I don't know the exact version that this started.
When switching to the market order tab the 'Place Order' button remains greyed out and unavailable even if adjusting the amount to buy. Clicking 'Reset Form' is necessary to be able to use a market order again.
Previously, I would be able to fill out order details in the limit order tab, then switch to the market order tab to have the purchase quantity filled in for me. Made it a lot easier to get an exact order size based on %/amount of capital.