Create a customizing request in SE01 in the front end system and maintain the value as given in this link in the transaction SU2 - Setting Default Transport Request Information from Back-End
Also verify that your user has all the necessary roles and authorizations required for accessing the launchpad designer in both front end and back end systems, as given in this page under the section Administrator: SAP Fiori launchpad Designer.
SAP Fiori LL20 - Role and Authorization settings for SAP Fiori launchpad
Regards,
Saurabh