The sequencer is one of a thousand features in UE4, I understand that bugs like this can be very annoying but you can’t expect them to take highest priority on this one considering there are problably a ton of even more game breaking problems. I stopped asking for fixes a long time ago because the response was always the same, letting your programmer fix the bug in the engine source is probably way faster. I am not using the sequencer so I am not really sure what the bug does or breaks, but I don’t see how version control and regular commits wouldn’t be able to prevent the “loss of several weeks of work”.
Like I said I don’t use sequencer and I could care less about this bug, but your response to someone who was trying to help you was pretty rude so yeah take a step back and realise that you are not the single most important person in the Unreal Engine community with your problems.