Thank you for contacting the support team.
The only reason I can think of why the page template disappears is that you have configured the widget to open the details of the blog post(when blog details are rendered the rest of the blog posts list will dissapear) on another page that don't have this template. I believe you get the default functionality, if the aim is to have a lit of blog posts at one place and the details of a selected blog posts on another place let me know.
Can you please open the blog post widget designer and in the section Single item settings check what page is selected. Note that the auto-generated page from the first radio button will open the details in a page with the same page template as the one on the current page.
It will be very useful if you could provide a video recording of the whole scenario.
I look forward to hear from you.
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