Key signature crashing with first note of bar

It seems there is a time signature between the ley and first note that has been disabled. Not sure how this happened, can you remember anything about how the score got into this state? I see you have disabled display of time signatures in staff properties, I guess that combined with the fact that there is a time signature change in this measure created the problem. Anyhow, click the key signature, hit Alt+right to select the disabled time signature, then hit Delete. And if you need to change number of beats in a measure in a score with time signatures disabled, don't use time signatures, but instead use Measure Properties (or just Ctrl+Delete a beat directly).