Hello Rowan,

It looks like there are some redirection going on from https://www.spanishmarks.com/timeline to https://www.spanishmarks.com/timeline/login . This actually caused the login to fail because the form is being POST-ed to /timeline and since there is a 303 redirection, it's causing the login to fail.

Did you apply any redirections for /timeline ?

No, no redirections.
With SEF completely turned off it will work however.
I had a similar issue before when I brought this up to 3.7.2 which turned out to be an authentication issue.
Last time I disabled the authentication cookie plugin and things went back to normal.
That plugin isn't enabled on this site so that's not it.

I've just changed the core login item to the easysocial login item.
So the entire thing sites on /login
Same thing happens.

Hello Rowan,

Hm, I have been debugging the site and it seems like the JInput is returning an empty value (not entirely sure why) but as soon as I disable the library "F0F (NEW) DO NOT REMOVE " under the manage extension and re-publish it again, it started to work again.

Can you give this a try and see if it works for you now?

Site is now working perfectly. That's just plain odd! Can't understand how simply disabling and enabling FOF would fix it, but I'm glad it did!
Thank you so much for your help.
I'm going to mark this as resolved now.
Rowan

Yeah, I am puzzled too. I wonder if opcache is caching those php codes but either way, I am glad that your issues are resolved now