QB Issue Resolution:

It looks like you caught a bug.  It is a beta feature (and Projects is new), so there are probably more bugs than usual. You can report it by clicking Gear>Feedback, where there is a Bug choice

Resolution for Issue 'Customer Types on Past Transactions' available: Yes (Solved).
Source: Intuit Community forum.

Customer Types on Past Transactions: this 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 issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for Bug choice
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