another stupid question; you do know that you need to adjust both pads on spyres? And that the pad adjusters on spyres are a bit crap and quite often back out by themselves? These things can cause the disc to get pushed into the caliper body if they are not attended to.
If I understand your measurements correctly then you have only worn ~0.6mm from your pads; they would each have been ~4mm total thickness originally and if you have 1.8mm of friction material and 1.6mm backings remaining that makes about 3.4mm total thickness.
This is only about half-wear on the pads but if you have only adjusted one pad not both (or the adjustment has backed out by itself), it is enough wear to allow the disc to get pushed into the caliper body on the side where the pad was not adjusted. That will make a terrible noise which will mysteriously be cured when new pads are fitted.