Capistrano is more prone to fungal root diseases than many other rhodendrons, so it's entirely possible it was already infected when you bought it. These root diseases flourish when the soil is overly wet and hot. Plants at the nursery in black containers placed in direct sun and overwatered can and do develop it rapidly.

Your sandy soil should supply the good drainage and aeration Capistrano needs as long as you did not plant it too deeply, but extended periods of direct sun are not good for any yellow flowered rhodendrons. Even if they grow OK - which most will not - direct sun bleaches out the yellow color.

If the nursery where you bought the plant offered any kind of warranty, I'd use it and replant in an area of more shade.

Thanks for the response.

If I move the capistrano and replant something else there, is there a danger that the new plant will become infected as well?

It gets afternoon sun for 2-3 hours. Any suggestions for other varieties that can handle a bit more sun, or other flowering evergreens that might do well there?

I bought a rhodedendron and also a azalia plant, we bought the proper soil to plant it in but the plant has lost all its leaves and looking pretty dead, what did I do wrong?
Did it have too much sunshine?

It's really impossible to help without more information. Such asvariety, planting technique, your local weather, appearance of the plants, etc.,etc.,etc.