Invocation IDs are identifiers for an instance of a service. You can find them under /run/systemd/units/. They used to be set as cgroupfs xattrs but since that required too much privilege and was dependent on kernel version systemd moved to the symlink model. The errors are fine. Everytime systemd moves on and doesn’t freeze an error message can likely be ignored (rule of thumb). What systemd version is this with opensuse? This should be a debug message in all recent systemds.