Webscraper.io

I’m using webscraper.io-addon for Firefox. But I have a problem what is causing scraping to stop without any clear reason. I wrote email to webscraper and they told:
“The issue is likely due to memory limitations in your browser, as the sitemap operates in a single continuous session without reloading the HTML at any point.”
So is there any way to figure out what limit exactly can cause this? How to record or track Firefox so I could precisely find out the problem what is causing scraping to stop? Then it might be possible to do something to it.