most of the ores have significantly higher market value when compressed. However, some - like Kernite - are the other way around and you can easily lose millions by compressing it. In my area, the average price for Kernite was almost twice the amount people paid for Compressed Kernite and it’s been like that for 2 months or more.
Have I missed anything? Is there a reason for this or was it just mere chance it became like this?
No idea why, just look at the opportunity. Work out the cost for you to refine, plus the market for minerals. If you can make a buck from buying and refining the compressed ore then get out there and buy up all the compressed you can. And then sell any regular that you mine yourself.
Kernite is a special snowflake as it is needed to complete a certain lvl4 storyline mission. So find you closest mission hub & the associated storyline agents and list your kernite there.