Don’t confuse Wix with Wix Code. The Wix part of it is working since many years for more than 120 million sites. Wix Code on the other hand is a beta product and many people has forgotten this, beta means not released for production, not stable enough yet… Then when working with data collections there is a lot of things to think about.
Is the dataset ready to work with? How many items does it load? How many elements do you have on your page.
What specific problems do you have?