Any update on this issue or a support case # you could share?
It is likely a permissions issue as in 7.1 jobs were executed by the windows task scheduler and a user account was specified that likely had permissions to that share. Now in 7.2 jobs are executed by the Orion platforms job scheduler which is likely running under the local system account. I will investigate this further to see if there is a work around.
In the mean time you could change the config archive to point to a local folder and have them copied every so often to the share. You could even use the windows task scheduler to create a basic daily task and have it run under the same user account you used in NCM 7.1's backup job.