We have considered the reported issue " MultiSelect displays "undefined" when virtualization is enabled along with custom preselected values " as a bug from our end and the fix for the issue will be included in our upcoming weekly patch release, which is expected to be rolled out in end of May , 2026 .
Will share the feedback details in following update ,
Disclaimer: “Inclusion of this solution in the weekly release may change due to other factors including but not limited to QA checks and works reprioritization.”