Thank you for your patience regarding this matter.
We had the chance to locate the problem causing your test to fail and it turned out it has pretty easy workaround. Just make sure you have the Dialog monitoring enabled by using this line:
Here is a short video
how this is working on my end.
The complete code should look like this and it should work perfectly fine on your end as well:
Manager Manager =
Browser Browser = Manager.ActiveBrowser;
AlertDialog alert =
handleCount = alert.HandleCount;
We will be including the fix for this in the internal build that we are going to release later this week, so adding the additional line will not be necessary.
Thank you for your understanding and patience regarding this matter.