Hi,
I did a test on my end.
When I don't have any prices in any of the variants of the product, there is no price column for the variants table, as it should be since they all have the same price:
take.ms/1FFHw
If however I set a price to one of the variants, then the price column displays and all the prices display on the variants table:
take.ms/GhVOr
In both cases, it works fine.
So on my end it works as intended.
Either you have a case we didn't thought about and are not able to reproduce, or you have a template customization on the show_block_characteristic view file which doesn't handle the price display properly.