You'll need to separate out the hash and the salt on the Import API.

For example, the hash $2a$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy would be split out to the fields:

factor: 10
salt: N9qo8uLOickgx2ZMRZoMye
password: IjZAgcfl7p92ldGxad68LJZdL17lhWy

The Import API does not parse this value and separate it out for you. You need to do so.

Here is an example import script (in Ruby): https://github.com/FusionAuth/fusionauth-import-scripts/blob/master/auth0/import.rb#L47