Item SKU's not pulling through

Hiya All,

I am running into an issue at the minute where every time I add a new product with separate attributes, if someone orders one of these items it doesn't pull through the SKU into orders, it just shows the parent SKU however all old products still work fine.

For example - Product Parent SKU - IDE546
                              Ordered Product SKU  - IDE546M
                              Shown in Orders SKU - IDE546

Hopefully the above makes sense.
I cant see any difference in product setup and everything has always been done the same so I am not too sure what could be causing it.
Has anyone else ran into this issue before?

Many Thanks

Are you using "Attribute Combinations"?  (Is that where you set the new SKU?)

I don't recall the specifics on when it's used.  What is your "Inventory method" ?
Maybe see if the other working products have  set "Inventory method" to "Track inventory by product attributes".