Sure, here’s what happened, in a nutshell:
You had placed a Limit sell order which was not confirmed by our Intermediary and thereafter another Limit order with the same quantity.
The orders were duplicated in a short period of time and you sold more quantity than you had owned, in reality, resulting in the opening of a short position, which is not allowed in the Invest environment. Therefore, an automatic Buy order was placed from the system in order to close the short position.
For additional reference, definitely make sure to check this post in another thread in the Community, as it describes an identical situation.
As always, if you need anything else -feel free to DM me 