Try logging off and logging back into Mac qb.  Open the data file.  Try again.  If that doesn’t work, contact support in the morning.

Resolution for 'Attempting export issue: 'Attempting export from Quickbooks Mac to online. Prompted to update, but newest version is installed. Verified & Rebuilt Data. No joy.' available: Yes.

The Attempting export issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Attempting export issue yourself by looking for a resolution described in the article. If it is a complex Attempting export issue or you are unable to solve the issue, you may contact us by clicking here or by using other Attempting export support options.

For more information about resolving issues related to Attempting export in Quickbooks/QBO or to get support for the issue 'Attempting export from Quickbooks Mac to online. Prompted to update, but newest version is installed. Verified & Rebuilt Data. No joy.', click the link below: