Anyone seeing strange Phone Extension warning message on Dep Ben Info Page?

We are testing Fluid Open Enrollment (PUM 37/Tools 8.57.20) and when I enter a new dependent or beneficiary phone in the Dependent Beneficiary Info Page, and select to use the same phone as the employee and pick the phone type (with no extension) I get the following warning pop up:

Invalid Extension :  

(18111, 4402)

Only numbers can be entered for Extension.

Is anyone else seeing this?

For my test cases, the extension value is null when this message displays. It happens with every case I have entered. I am permitted to save, so it is a warning but it seems unnecessary as most dependents and beneficiaries will use a phone that does not contain an extension.