Odd that the whole planting would revert to green en masse, all at the same time, but unless the leaves are just now unfolding and the variegation will manifest a bit later that would seem to be the case. If the green persists you could try cutting some of the oldest stems back, to see if variegation reappears on replacement shoots.

variegation is genetic ... the odds of it changing due to a soil problem are infinitesimal ... and if your soil was so out of whack.. i doubt the plant would survive ...

i too recommend waiting to see if the color develops ... especially if you have had a cold spring ....

i doubt they are grafted.. so i would not suspect a root stock issue ..

let us know ... a picture might help us...

ken

Thanks for the input. We have had a cold, rainy spring so far. I'll give it some time and see the variegation shows up as the leaves mature a little.