The commends in here remind of me of an incident earlier this year when news websites reported that an Italian band called "Soviet Soviet" had been denied entry to the US and deported even though they were scheduled to play at SXSW. The reason was because they entered on a visitor visa but were denied because "musical performance" is classified as work, and you cannot work on a visitor visa in the US.
The incident caught the media's attention because this happened around Trump's Muslim ban but actually had nothing to do with it because they simply applied for the wrong visa.
It looks like the same thing has happened here but instead of Trump, people are blaming China. Maybe if your favorite musician had applied for the right visa, none of this would've happened. Yes, Hong Kong has immigration law too.
Italian Band Soviet Soviet Denied Entry To The U.S., Jailed And Then Deported : The Record : NPR