Woocommerce not saving product variations

Hello

I am using the latest version of woocommerce. The plugin now seems to have stopped saving product variations. I have about 30 variations on my product so far and need to add about another 100 but it has stopped saving the variations. The new variation is created after I update the product but all of the fields that I have filled in (price, sku and attributes) are blank(for textboxes) or unselected (for the attribute dropwdowns)

Is this a known bug in woocommerce? Is there any upper limit on the number of variations I can have?

Thanks