I recently got an Issue with this. And I shared my screen with support and we figured out that for certain files (PDF created from CAD software) keep opening the right panel, because they have it in their properties, like each files has its own property to open the page and the panels, so in order to keep this file from opening the panel you have to change this property and save it, so the next time you open it wont open the panels. It's so annoying
I recently got an Issue with this. And I shared my screen with support and we figured out that for certain files (PDF created from CAD software) keep opening the right panel, because they have it in their properties, like each files has its own property to open the page and the panels, so in order to keep this file from opening the panel you have to change this property and save it, so the next time you open it wont open the panels. It's so annoying