The "progress meter", if you were refering to the bar displayed during page load, has been removed from Firefox a while ago, not recently in to the 54 to 55 update.

Would it be possible you were using an add-on for this purpose that might have been disabled in Firefox 55, such as Loading Bar or Status-4-Evar? The last one is known to no longer work in 55, but you can try its beta/development version (see its reviews and the bottom link on the AMO page).

I was using Status-4-Evar, but neither it nor its beta works for me. I guess it's just another case of the devs removing a feature simply because they personally don't need it without asking if anybody else uses/wants/needs it.

Just about to ask about this. Status-4-Evar seems to have been disabled. I can almost deal without the progress bar, but I can't even see the status text when scrolling over a hyperlink. I need this feature back.

EDIT: So I went into "options" on my Status-4-Evar add on and simply hit "ok" and now the status bar and status text are showing back up. Weird.