Hi Junyi Cheong,
Thanks for using Syncfusion Products,
We have validated your query and we were unable to reproduce your reported issue when following the getting started document. Could you please ensure that whether the target is set properly for Dialog component?
Please share a sample by modifying the above sample with reproduce your reported issue, or provide sufficient information to reproduce the issue in our end. So that we will validate and provide prompt solution on this.
Regards,
Narayanasamy P.