Hi, I was able to identify this bug as something unrelated to only closing your browser.
In a nutshell, if you close your browser and then reopen it, our longstrip reader will force you to the first page because it thinks you're reloading the page. Forcing you to the first page in longstrip mode after reloading the page is an intended behaviour, so I'm not sure if this can be fixed.
Still, I opened an issue ticket about it.