There can be a number of reason. Safety used in special case.
- Is the machine homed ?
This can be checked by looking at the DRO, the the DRO text is white this indicates that the machine has been homed.
- Are there 'slow feed' triggers ?
Another reason could be that one or more AUX inputs have been configured to be 'slow feed' triggers. This means that if such an input is active, the machine should only use the slow feed to move.