完成$sudo snap set system experimental.parallel-instances=true并重新启动后，我能够并行安装多个应用程序。例如：
$ sudo snap install zoom-client skype instagraph
2021-08-04T15:51:12+08:00 INFO Waiting for conflicting change in progress: conflicting slot snap snapd, task
"connect"
zoom-client 5.7.4-28991.0726 from Oliver Grawert (ogra) installed
instagraph 0.4 from Turan Mahmudov (turan-mahmudov-l) installed
skype 8.74.0.152 from Skype✓ installed
但是，当应用程序需要--classic限制时，我注意到并行安装命令不起作用。例如：
$ sudo snap install zoom-client slack --classic
error: a single snap name is needed to specify mode or channel flags
我应该如何克服/处理这个问题？