I have 2 Samsung Galaxy S4 mini devices. They are the same model, GT-I9195, running the same operating system, LOS-17.1, and the same Firefox, version 86.1.1, with the same settings. One of them will open the HTML file that I author'd as a sort of homepage launch screen. A copy of the file is stored on the removeable SD card in each device. One of the devices opens and displays the file nicely, the other shows a totally blank page; and, every other HTML file I have written and saved on either internal or external storage shows blank on either device. It's almost as if the one file that does open maybe shouldn't, arrgh. Firefox used to open all the HTML files I wrote, but that was with version 68 and earlier on Pie and earlier. How can I get version 86 to show all my HTML files on Android 10 ???

Here are a screenshot of the 1 file that will open from storage, and a 2nd screenshot showing what displays for any other HTML file. By the way, the 1 that shows may have been sort of grandfather'd in from having previously been set as a customized homepage in many earlier versions of Firefox. Any help, ideas, or things to try will be appreciated.