I got another reply from IBKR a couple of hours ago. They just repeated that the issue is with the developers, and stated there is no current timeline for resolution.

?

I responded pointing out that this is a significant matter, not just a trivial inconvenience. I also expressed surprise that they haven’t simply rolled back whatever change they made that caused the problem.

?

I don’t expect to get any meaningful further feedback until some progress is made with fixing the problem.

?

It might be worthwhile others also raising tickets to express their dissatisfaction. (Or it might not…)

?