I received four errors on my CRA submission that are all coded Q300 - "Average loan amount of small business loans originated > $250k not <= $1 million". What does this mean and what am I supposed to do about it?

Nothing, it is just a red flag. If you are sure your numbers are correct then you sign off and go on.

Actually this means that somewhere in those geographies you have entered a "small business loan" with an origination amount greater than $1 million. You should remove these loans and resubmit.