It seems that if you update Atlas UI module in the Polarion Connector Sample App, it starts to conflict with the feedback widget in PL Atlas UI and thus gives the message that you have noted in your post. Moreover, I observed that the Siemens PL UI theme also gets clobbered somehow with the updated Atlas UI. So, instead of updating the Atlas UI module, here is my alternative suggestion to you –
Download a fresh copy of the Polarion Connector Sample App and open its project in Mendix Studio Pro 8.15.2. Since the errors that show up are coming from 3 of the building blocks of native phone lists in the Atlas UI (List_Item_Swipe_IconText, List_Item_Swipe_Icon and List_Item_Swipe_Text), which we do not make use of in this App, go ahead and resolve these errors by picking the resolution presented by right mouse clicking on the errors. Once you get rid of the errors, the App should build and run fine by choosing Run Locally. I’m pasting below some self-explanatory pictures for your quick reference.
Thank you for the help. This solved my problems. It works !!