Update: This is the full output of `systemctl show mnt-backup.mount`, it was truncated in my previous message.
TimeoutUSec=1min 30s ControlPID=0 DirectoryMode=0755 SloppyOptions=no LazyUnmount=no ForceUnmount=no Result=success UID=[not set] GID=[not set] MemoryCurrent=[not set] CPUUsageNSec=[not set] EffectiveCPUs= EffectiveMemoryNodes= TasksCurrent=[not set] IPIngressBytes=[no data] IPIngressPackets=[no data] IPEgressBytes=[no data] IPEgressPackets=[no data] IOReadBytes=18446744073709551615 IOReadOperations=18446744073709551615 IOWriteBytes=18446744073709551615 IOWriteOperations=18446744073709551615 Delegate=no CPUAccounting=no CPUWeight=[not set] StartupCPUWeight=[not set] CPUShares=[not set] StartupCPUShares=[not set] CPUQuotaPerSecUSec=infinity CPUQuotaPeriodUSec=infinity AllowedCPUs= AllowedMemoryNodes= IOAccounting=no IOWeight=[not set] StartupIOWeight=[not set] BlockIOAccounting=no BlockIOWeight=[not set] StartupBlockIOWeight=[not set] MemoryAccounting=yes DefaultMemoryLow=0 DefaultMemoryMin=0 MemoryMin=0 MemoryLow=0 MemoryHigh=infinity MemoryMax=infinity MemorySwapMax=infinity MemoryLimit=infinity DevicePolicy=auto TasksAccounting=yes TasksMax=4915 IPAccounting=no UMask=0022 LimitCPU=infinity LimitCPUSoft=infinity LimitFSIZE=infinity LimitFSIZESoft=infinity LimitDATA=infinity LimitDATASoft=infinity LimitSTACK=infinity LimitSTACKSoft=8388608 LimitCORE=infinity LimitCORESoft=0 LimitRSS=infinity LimitRSSSoft=infinity LimitNOFILE=1048576 LimitNOFILESoft=1048576 LimitAS=infinity LimitASSoft=infinity LimitNPROC=127987 LimitNPROCSoft=127987 LimitMEMLOCK=67108864 LimitMEMLOCKSoft=67108864 LimitLOCKS=infinity LimitLOCKSSoft=infinity LimitSIGPENDING=127987 LimitSIGPENDINGSoft=127987 LimitMSGQUEUE=819200 LimitMSGQUEUESoft=819200 LimitNICE=0 LimitNICESoft=0 LimitRTPRIO=0 LimitRTPRIOSoft=0 LimitRTTIME=infinity LimitRTTIMESoft=infinity OOMScoreAdjust=0 Nice=0 IOSchedulingClass=0 IOSchedulingPriority=0 CPUSchedulingPolicy=0 CPUSchedulingPriority=0 CPUAffinity= NUMAPolicy=n/a NUMAMask= TimerSlackNSec=50000 CPUSchedulingResetOnFork=no NonBlocking=no StandardInput=null StandardInputData= StandardOutput=journal StandardError=inherit TTYReset=no TTYVHangup=no TTYVTDisallocate=no SyslogPriority=30 SyslogLevelPrefix=yes SyslogLevel=6 SyslogFacility=3 LogLevelMax=-1 LogRateLimitIntervalUSec=0 LogRateLimitBurst=0 SecureBits=0 CapabilityBoundingSet=cap_chown cap_dac_override cap_dac_read_search cap_fowner cap_fsetid cap_kill cap_setgid cap_setuid cap_setpcap cap_linux_immutable cap_net_bind_service cap_net_broadcast cap_net_admin cap_net_raw cap_ipc_lock cap_ipc_owner cap_sys_module cap_sys_rawio cap_sys_chroot cap_sys_ptrace cap_sys_pacct cap_sys_admin cap_sys_boot cap_sys_nice cap_sys_resource cap_sys_time cap_sys_tty_config cap_mknod cap_lease cap_audit_write cap_audit_control cap_setfcap cap_mac_override cap_mac_admin cap_syslog cap_wake_alarm cap_block_suspend cap_audit_read AmbientCapabilities= DynamicUser=no RemoveIPC=no MountFlags= PrivateTmp=no PrivateDevices=no ProtectKernelTunables=no ProtectKernelModules=no ProtectKernelLogs=no ProtectControlGroups=no PrivateNetwork=no PrivateUsers=no PrivateMounts=no ProtectHome=no ProtectSystem=no SameProcessGroup=yes UtmpMode=init IgnoreSIGPIPE=yes NoNewPrivileges=no SystemCallErrorNumber=0 LockPersonality=no RuntimeDirectoryPreserve=no RuntimeDirectoryMode=0755 StateDirectoryMode=0755 CacheDirectoryMode=0755 LogsDirectoryMode=0755 ConfigurationDirectoryMode=0755 TimeoutCleanUSec=infinity MemoryDenyWriteExecute=no RestrictRealtime=no RestrictSUIDSGID=no RestrictNamespaces=no MountAPIVFS=no KeyringMode=shared ProtectHostname=no KillMode=control-group KillSignal=15 RestartKillSignal=15 FinalKillSignal=9 SendSIGKILL=yes SendSIGHUP=no WatchdogSignal=6 Id=mnt-backup.mount Names=mnt-backup.mount Description=mnt-backup.mount LoadState=not-found ActiveState=inactive SubState=dead StateChangeTimestampMonotonic=0 InactiveExitTimestampMonotonic=0 ActiveEnterTimestampMonotonic=0 ActiveExitTimestampMonotonic=0 InactiveEnterTimestampMonotonic=0 CanStart=no CanStop=yes CanReload=yes CanIsolate=no StopWhenUnneeded=no RefuseManualStart=no RefuseManualStop=no AllowIsolate=no DefaultDependencies=yes OnFailureJobMode=replace IgnoreOnIsolate=yes NeedDaemonReload=no JobTimeoutUSec=infinity JobRunningTimeoutUSec=infinity JobTimeoutAction=none ConditionResult=no AssertResult=no ConditionTimestampMonotonic=0 AssertTimestampMonotonic=0 LoadError=org.freedesktop.systemd1.NoSuchUnit "Unit mnt-backup.mount not found." Transient=no Perpetual=no StartLimitIntervalUSec=10s StartLimitBurst=5 StartLimitAction=none FailureAction=none SuccessAction=none CollectMode=inactive