Only clients with at least one hourly project that falls within the min/max rate range defined for a My Time59 user will appear in the drop down list when entering time or expense records in My Time59.
The solution to the "missing" client problem is to add a project for that client that is within the min/max rate range, or to change the settings for the My Time59 user's min/max rate range.
You may also contact us using the Feedback form or at support@time59.com.