The absence of proof is not always proof of absence.

Not having found something can mean it is not there, or that you have not looked in the right place, or that it would not leave a trace even if it were. Which of these applies depends entirely on how thoroughly you searched and whether evidence would be expected. Treating any absence as settled runs both ways and misleads in both directions.

Before concluding from a gap, ask what evidence you would expect to see if the thing were true and whether you have actually looked there. If you have searched properly, the absence means something. If you have not, it means only that you have not searched.