We also encountered this BUG, and still not fix yet, which making our website malfunction as we rely on this feature. Wix change something under the covers and not informing us.
And the most annoying thing is, the openLightbox function cannot handle opened lightbox, and Wix don’t have closeLightbox function as well to force some opened lightbox to close.
This is just simple UI control features, and should be easy for Wix engineer to implement.