Sedums and lewisia

I have a raised alpine bed. Base is various garden rubble, then large gravel, sandy soil (about 5”) then fine gravel. Full sun.
I have 2 sedums and my second (as in, I’ve killed one already) lewisia looking very small and struggling this year. I don’t fertilise, is that worth trying? Thanks
Edit to add pics. You’ll have to look very carefully for the 2 sedums The lewisia doesn’t look rotted by water?

 

Sounds good, I think it sounds ideal.
Although I think Lewisias are best planted on their side to stop the water laying in the rosette.
Probably lots of other things you could try.

 

I agree about Lewisias, they are usually planted in a wall so that rain doesn't collect in the rosette.
You could try a feed, but I would only do it once.
Maybe there isn't enough soil for the Sedum sieboldii (that's the first one)