why are all leaves of yucca plant broken

Question

All leaves of 4 yucca plants are broken off

Answer 1

You didn't mention whether the plants may have had snow or cold damage over the winter, but if so, here's an article that may be helpful: https://www.gardeningknowhow.com/ornamental/foliage/yucca/yucca-cold-weather.htm

If this is a houseplant, there may be other issues. Did the leaves turn brown before breaking off? Here's another article with helpful info:
https://www.gardeningknowhow.com/ornamental/foliage/yucca/yucca-turning-brown.htm