Going back a long way to my student days and yes feeds and speeds could well be a contributing factor..
Aluminium has characteristics which are problematic . Built Up edge was always a problem with aluminium where a ball of plasticised aluminium builds up on the cutter, interfering with free cutting. A decent cutting oil will help but if all else fails some WD40 will improve matters a little.

It is also significant that a 1mm cutter is part of the process. I suspect that it came from the far east and the quality may be questionable to say the least .
Are your spindle revs adequate to give decent cutting speeds at this diameter ?

To my mind known science with regard to cutting speeds is hard enough to achieve with cutters at 3 --6 mm cutters .