New build does not reach external testers

I recently ran into an issue that I don't understand. I've uploaded a new version and submitted to test by Beta App Review. It takes about 1 day and the status had changed from "In review" to "Testing". I've already assigned that build to External tester group but the app has not been updated in the Testflight app and testers only see the old builds. Should I wait or update new build?

Hi, I'm having same problem. Did you manage to solve this, @NangSawOhnmar

New build does not reach external testers
 
 
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