woocommerce variations disappearance

Probably because you can not have duplicate SKUs, can be what is happening with you. Each product/variation need an unique SKU.

Hello Claudio,
first of all I want to thank you for your help.

I dont think is this the problem, because I did different test copying a product with and without the SKU, and the problems persist.
Also sometimes, the copy product, did not allow me to write a SKU. (either if i copy a product without sku)

Its like some kind of instability, because it sometimes works like this and sometimes it works perfectly.

Another problem is that I cant edit a finished product because it change me the variations and prizes.

Can you replicate this with a test case (maybe less variations?) and post the steps you did?

Ciao Mike sure,
this is how i do it:

I create a variable product, write the title, description, e sku first,
then I choose the attributes and create de variations.
First of all, one variation with whichever/whichever/whichever and i give it a prize,
afterwards I create the other variations, all of them with color variation in whatever, and write the prize. (I didn’t write the sku in the single variation because I want just one for the product independently of its variations)
After all I save the product and post it.

The problem arrives with the second product.

I copy the first one,
change the name and the sku, (the sku sometimes didn’t me allow me to be modify, or sometimes directly disappears)
change the attributes and variations prize, and post the product.
When I do the check, at the published product to see if everything is going well, sometimes there are some variations deactivated, sometimes everything is okey.

And I cant understand how it happens.
Everytime I modify anyone of my product the variations change.

Thank you for your time Mike.

Using the same skus won’t be allowed. After you duplicate it, use new skus. I don’t see anything in the code which would change status of variations – they are duplicated with the exact same status.