Shrimp keep going MIA

[mark]

Can't seem to keep cleaner or peppermint shrimp more than a few months. They seem healthy, regular molts etc but after a while just disappear without a trace.

Tanks a reef and usually doing good though currently having some problems with the SPS, but last time with shrimp was well before this.

Fish are Purple and Regal Tangs, Foxface, Sixline, clowns ands damsels., have a few BL hermits also.