what is your EA HR version?
please check whether the button is greyed out with using the standard HRESS_AC_PTARQ_LEAVREQ application configuration (direct-call). Furthermore please make sure the SAP_HR and EA-HR software packages are in sync - please upgrade with the help of MOPZ. or check here Comparing and synchronizing the attributes from the standard configuration 'HRESS_AC_PTARQ_LEAVREQ' can resolve the issue if you are using custom
The 'Component' attribue in the custom configuration contained the value 'FPM_FORM_UIBB' where this attribute was cleared in the standard configuration. Check in your custom OVP configuration whether there is a component maintained in the attributes of the buttons SEND_AND_NEW and SEND_AND_BACK. If so, then the button properties 'Visibility' and 'Enabled' are no longer controlled by the OVP itself but by the maintained component and the corresponding feeder class.
The OVP then tries to get the properties via the IF_FPM_UIBB_API. However, if the component or the assigned configuration cannot be found the button is automatically set disabled and visible.
FPM_FORM_UIBB in component of attributes of the button element in HRESS_CC_PTARQ_LEAVREQ