This is caused by DE40567.
This issue is tentatively planned to be fixed in CA PPM 15.5.
The description of the access right for 'Resource - Soft Book - All' is incorrect in PPM. It should read 'Allows user to Soft book all resources to an investment that the user has been granted project edit management rights or investment edit rights. The right also allows the user to edit or remove any soft-booking for the specified resource'.
Note: The description for this right is only incorrect at the Global level. It is correct for Instance and OBS Unit level 'Resource - Soft Book' access rights.