Not seen, not sold...

If your new stuff is not selling, then consider why... Are you not putting enough effort into keywords? (poor keywords == not seen == not sold).  Are you still producing quality that worked a decade ago? (competition is stiffer now, and buyers more sophisticated. Stuff that sold a decade ago won't rise to the surface now).

Personally a large part of my sales is always stuff that is less than 6 months old.  Roughly half is from stuff up less than a year, with the other half being stuff I put up more than a year ago.

I can definitely see a jump in sales when I start submitting again after a lull.  I took 6 months off (traveling) and sales were drooping.  Added a bunch of new stuff over a 2 month period (from those 6 months travels), and my sales doubled for the next few months.

Sometimes it feels like the SS system is rigged, you only get paid a % of what you contribute to them for as long as you keep contributing and they report these 'sales' to you - more like a system than picks up random images in your port  (if you keep uploading daily or weekly, your sales go up, if you stop uploading for a few weeks or months, your sales go down). Are they actually being audited by an external agency?

Why wouldn't they  simply push regular contributors higher in algorithms I can't see anything wrong with that?

I noticed the last half year, that only new editorial images sells.
Maybe my other images aren't good enough

I have been uploading more since a few months an have more sales (but not enough )