How do you have the Fixed Port / Ephemeral Port mode set? The way you described your first issue (with the second object not able to attach unless the first object launches Blue Prism), this sounds like expected behavior if you have Ephemeral Port mode on. That would mean you have the checkbox at the bottom of the Settings page in the system tab UNCHECKED. If you do have it unchecked, then it is apparently expected (according to Blue Prism) that you cannot attach to a manually-launched instance of the browser. Only if you CHECK that box (which turns Ephemeral Port mode off and thus turns Fixed Port mode on) will you be able to attach to manually-launched instances of the browser. And note that if you decide to change this setting, restart the Interactive Client machines (whatever you develop on) as well as any runtime resources.
For your second issue with Win32 mode not working, I've never encountered Win32 mode not working. Have you tested whether Win32 works when you attach to Chrome as if it's a Windows application? That is, change the application modeller's application type to Windows app by going back through the wizard.
The last thing I wanted to mention is based on what I gather from some of the replies in this thread. I do not ever use the Child Index for attaching in Chrome automation. It's just as others have said, it's really only a thing in IE automation. What I've found is that using the Attach button inside of Application Modeller does not work for Chrome automation. It just simply is completely useless. If you want to attach to an instance of Chrome, use a navigate stage to attach and step over it. Then you can open app modeller and start spying elements and such. There is more info surrounding this, but I don't want to complicate this discussion at the moment. The other piece that is important here is that Fixed/Ephemeral Port setting. To avoid that whole issue, just make sure that Blue Prism is always what launches the browser instance so that attaching will work.
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Dave Morris
Cano Ai
Atlanta, GA
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Dave Morris, 3Ci at Southern Company