According to this reddit thread, some IBKR customers' portfolio were down by 100% temporarily due to a bug. The biggest nightmare is that the system went into auto-liquidation mode if it mistakenly believes that margin was seriously impacted due to the portfolio "crash". Did anyone experience such a nightmare due to the bug? I personally did not and have so far had good experience with IB platform. After today, I'm sure many customers will be left disappointed and worried even.
@nooby_mcnoob mentioned that he lost his IB sim account: https://www.elitetrader.com/et/threads/nooby-mcnoob-becomes-a-quant.307995/page-16#post-4619711 I monitor my IB live account every hour and haven't noticed anything exceptional in the last few days. Certainly not to the extent of "entire portfolio value down".
It does seem to me that something is wrong with a release of the backend that they made on Tuesday. They still haven't been able to reinstate a paper trading account for me.
I trade fully automatic, so don't worry: I do not sit 24 hours per day in front of the computer screen. My trading currently involves instruments in Korea, Singapore, Germany and the US. So yes, it is almost 24 hours per day operational. As a monitoring tool do I download the account values every hour and store it in a spreadsheet (e.g. account value, maintenance margin). I didn't see anything special in this spreadsheet.
It is dangerous to trade automatic if the data is unreliable. IBKR market data is not reliable enough to give one the confidence to trade automatic. Just look at what happened today. If portfolio suddenly drops so much, all your cut-losses will be hit.
The impact will depend strongly on what safety valves have been built into the system. And on how the system responds to changes in the account value. In other words: how the system has been implemented. I wouldn't immediately judge all automated trading systems.
I know you were specifically asking for people who had problems, but maybe to help to reassure you, I held positions overnight in 8 different underlyings (US equity options) and I was not liquidated. However, I do see a single bulletin that appears to be related: Perhaps it was a display only bug. EDIT TO ADD: Just received another bulletin: From this one it sounds like it could be more than merely display as they are admitting orders may have been cancelled. Hopefully it's not more than that.
Every broker has problems, but why would anyone suffer everything that happens at IB? Are they really that good the other 99% of the time?