Flexpricer is a user-licensed managed package in Salesforce, which means that in order to access the objects, fields and functionality of the app, a user must be allocated a license.
When you install a new managed package into your org, Salesforce creates a user record for your package. This user record is not accessible or editable using standard salesforce tools.
If the new managed package needs to access fields within Flexpricer, then you will need to configure that package to run as normal Salesforce user who has a Flexpricer license.
If you do not do this, then you may receive a ‘not API accessible’ error or a silent failure that the fields are not accessible.
The Flexpricer Support team have seen this in a small number of cases with scheduled jobs run by the Rollup Helper app.
To allow this app to access Flexpricer fields, you should configure Rollup Helper to run the batch job as a specified normal user and not as the managed package user created when it was installed.