The billable expenses feature is available only in QBO Plus – is that what you are using?
If so, see below.
Resolution for 'Bill splits issue: 'Bill splits for Expenses' available: Yes.
The Bill splits 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 Bill splits issue yourself by looking for a resolution described in the article. If it is a complex Bill splits issue or you are unable to solve the issue, you may contact us by clicking here or by using other Bill splits support options.
For more information about resolving issues related to Bill splits in Quickbooks/QBO or to get support for the issue 'Bill splits for Expenses', click the link below: