Set Default New Task Type to Null Value

Is it possible to set the default task type for a new task in Mobile Field Service Laptop 11.5.10.2 to a null value? We have tried setting Task Manager: Default Task Type to Null at the site level, but this did not change the value in MFS after running JTM Lookup and synching.

The problem we are trying to resolve is an engineer goes on an installation and needs to return a second day to complete the installation. We require a new task for the return visit. The value currently defaulting is Field Service Visit. In this scenario the engineer should change it to Installation however, many times they forget or are not paying attention so we would like to set it to a null value since it is a required field and they would then be more likely to select the correct task type.