Tokens empty for single variation creation

I use product type that has only one variation.
We use single variation form when creating product (product is created along with variation)

We have this setup:
PREFIX-[token-modifier:upper-case:token-modifier:dashes:token-modifier:urlencode:commerce_product_variation:title:value]
Try this if you think about our additionall token-modifier (this is vanilla):
PREFIX-[commerce_product_variation:url:args:join-path]

We try commerce_product_variation only and this is populated AFTER FIRST SAVE of product.
When creating new empty one it will give only "PREFIX-" and we must empty field, then click save and get full proper one populated with tokens

Process of form is somehow different when having multiple variation in different page

Two option:
a) fix it by ding automatic sku after form is populated in code (proper placement of generating it)
b) add note about limitation