I also have a Yasha and candy cane shrimp. Love it. I was lucky and they paired right away. But be patient and can take awhile. They will find each other. I thought my pair died then 2 months later I found them both on my sump. The shrimp I'm sure is finding food. But sometimes I cut a partial frozen cube and stick down his burrow before it is thawed out. He will take the whole piece into his burrow. I'm sure food for a week.
I also don't see my shrimp unless goby is out and it took almost a year to see them on a regular basis. Now they come out whenever I feed. Also still very skittish.