"Cannot find variant", variant displaying wrong price in draft mode

[eljuderino]

My product is set up with a couple of variants. All variants are the same price (£30) and set to not track inventory.

I'm experiencing some unusual behaviour in draft mode:
When the product preview loads, variant 1 is selected and shows the correct price. If I select variant 2 the price shown changes to £19.99 (I don't have any variants at that price, on any product), and shows as sold out. If I select variant 1 it now shows the wrong price at £19.99 and is sold out.

If I load the preview again and don't change the variant options and try adding the product to the cart I get I get the "Cannot find variant".

The strange thing is, if I publish this product the errors go away.

I'm using the default template and Dawn version 12.0.

I can't figure out why this is happening, so any insight would be appreciated.