This behaviour is intentional, to avoid problems with customization changes.
It is expected that the Catalog GA installer should set the filestore path for every catalog node installation. In a normal scenario, we recommend the customers to install all nodes, set up LB and then update the OOTB FileStore location to the shared drive location via UI in their LB URL. We don't control this and cannot automate this from any of the patches.
Only way is to update the usm_configuration DB table filestore information as a last step.
NOTE: Any incorrect update in this configuration table will lead to the corruption of the data and application which cannot be restored.
select * from usm_configuration where group_name like '% filestoreconfiguration%' and name = 'documentroot'
update usm_configuration set value = '<<SHARED FILESTORE LOCATION>>' where name = 'documentroot' and group_name like '%filestoreconfiguration%'
Upgrades and patches can include updates to the file store contents, even before the requirement to re-apply any customization. The change is made to ensure the UI will at least become available after install.