QB Issue Resolution:

The easiest view for this is Lists menu > Add/Edit Multiple. Select that you want to see Customers, select the button for Customize Columns, and bring to your view what you want. You can make entries here and make sure to hit SAVE once in a while.

Resolution for Issue 'How do I fix missing information after importing customer list into new company? I have data missing, telephone numbers, etc.' available: Yes (Solved).
Source: Intuit Community forum.

How do I fix missing information after importing customer list into new company? I have data missing, telephone numbers, etc.: 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.

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