What is the secret to formatting an Account type field for a csv upload? I've tried just using {#####}, {##### Name}, {Name}, changing the field type to internal id and using that within the CSV import settings, nothing works. I've tried dozens of times. I'm about to give up and write a script.

I assume the {} are not part of your import? If so, definitely get rid of those. Otherwise, the value in your source file just needs to exactly match a value in the Type field. Maybe try a TRIM formula in Excel? Maybe you have spaces before or after the words? I've honestly never had trouble importing accounts so there must be something screwy with your source data. What error are you getting?

Resolved. I'm not importing Account Type btw, I'm importing Account. No idea why internalId doesn't work properly, but the format it wants is {Child Acct #} {Parent Acct Name} : {Child Account Name}.