PowerProtect Backup Services: Prebackup and Postbackup scripts do not run

Prebackup and postbackup scripts are in place. However, the execution does not run. 

The following error displays in the job log:

level=info ts=2023-05-11T13:19:54.933937279+10:00 filename=prepost_script.go:114 message="Running Script : /<path>/pre_script.sh for request_id : 46"
level=error ts=2023-05-11T13:19:54.934454653+10:00 filename=prepost_script.go:130 message="Exception encountered in executing the script"
level=error ts=2023-05-11T13:19:54.934499706+10:00 stack="fork/exec /<path>/pre_script.sh: exec format error\\ngoroutine 1 [running]:\nruntime/debug.Stack()\n\t/usr/local/go/src/runtime/debug/stack.go:24 +0x65\nphoenix/pkg/client/logutil.Error({0xcee3c0, 0xc0002643f0}, {0xc3e9b6, 0x1}, {0x0, 0x8, 0x8})\n\t/bld/src/phoenix/pkg/client/logutil/logger.go:86 +0x211\nphoenix/fileserver/client/agent/backupagent.(*BackupAgent).scriptRunner(0xc0000cb560, {0xc00026a138, 0x18}, 0x258, 0x1, {0xc2504c, 0xa})\n\t/bld/src/phoenix/fileserver/client/agent/backupagent/prepost_script.go:130 +0x815\nphoenix/fileserver/client/agent/backupagent.(*BackupAgent).runScript(0xc0000cb560, {0xc2504c, 0xa})\n\t/bld/src/phoenix/fileserver/client/agent/backupagent/prepost_script.go:89 +0x212\nphoenix/fileserver/client/agent/backupagent.(*BackupAgent).runPreScript(0xc0000cb560)\n\t/bld/src/phoenix/fileserver/client/agent/backupagent/prepost_script.go:23 +0x98\nphoenix/fileserver/client/agent/backupagent.(*BackupAgent).DoBackup(0xc0000cb560, 0x20)\n\t/bld/src/phoenix/fileserver/client/agent/backupagent/backup_agent.go:158 +0x352\nmain.backupMain({0xc0000a2160, 0x2, 0x1}, 0x0)\n\t/bld/src/phoenix/fileserver/client/cmd/PhoenixFSBackupAgent/main.go:174 +0x9b7\nmain.main()\n\t/bld/src/phoenix/fileserver/client/cmd/PhoenixFSBackupAgent/main.go:203 +0xa8\n"
level=info ts=2023-05-11T13:19:54.934512521+10:00 filename=backup_agent.go:966 message="Sending log to Phoenix server with message: Pre-Script error encountered : fork/exec /<path>/pre_script.sh: exec format error"
level=info ts=2023-05-11T13:19:55.180236915+10:00 filename=prepost_script.go:90 message="Script execution done with status : Failed"

In one instance where this issue is observed, #!/bin/bash is not in the pre_script.sh and post_script.sh. 
It works fine after adding #!/bin/bash to the first line of pre_script.sh and post_script.sh.