If your short position has been removed, you're using the "Do not buy back on loss" setting. You can change this setting in your Shorting settings of the Base config.
When is this feature activated?
When enabled, your trading bot will remove the short position instead of closing it, or in other words, it will not buy back the currency when the buy signal comes in when the short position is not in profit.
In this case, the trading bot will remove your short position, and your reserved funds of the quote currency will become available to open new positions.