simplify page in firefox

For several months, the "Simplify page" option in the page preview mode of Firefox has failed. I thought the problem was Firefox, but recdently tried it on my Debian machine with the same revision of Firefox worked flawlessly. Can someone suggest how to address the issue in Slackware 14.2 with all current revisions applied?

Thank you.

Are you talking about the "Reader View" icon that resides on the right side of the address field? If so, not sure what would cause that.

No. Let's say you go to a newspaper column and would like to print but you only want the text of the column, not the ads on the side. If you go to "print preview" option from the file menu preview screen appears. There is a check box at the top labeled "Simplify Page." At one time in Slackware a few seconds later the page would be reformatted eliminating most of the unwanted screen, but clicking it now does nothing. This is not the case with either of my Debian machines.

It's working fine in this VM of Slackware --Current with FF v. 68.6.

I never noticed that capability before. Thanks.

Cool, a feature I didn't know about. Slackware64-current here.

I doesn't work on the forum. I tried other sites, some sites it works, some it says it working but nothing happens and other sites it's disabled.