To reproduce the issue:

1. Create a product attribute using the measurement field
2. Select e.g Volume and as base unit "US liquid gallon"
3. save the attribute
4. Re-edit the attribute created 

Expected

• In the "Base unit" you have "US liquid gallon" as unit

Current Issue:

• The "Base unit" is empty. If you open the select option list you get the options of the first "Measurement Type" , in this case "length"

Below is a screenshot attached