seems the silver reserves are fine after all, page-2

All a bit contradictory, TTM. After all, on Monday, it WAS all about the grades in the announcement! That's why the first sentence of the Ann. was:

"CCU announced today that lower grade ore was impacting silver production ..."

The second para. says "lower grade ore is arising from two sources" - they only have two sources atm, and they are both lower grade than expected ...

Third para is all about grades too!

Yep, it's all about grades still. And yes, they mentioned that the grade variability was discovered by the grade control drilling on Monday too.