After editing the left sidebar widgets, and seeting them ok on the site, after a minute with a refresh it goes back to default and I have only the category widget there.
Ok. So it just happened again. What I noticed, though, is this:
all of my widgets moves from the “Left Sidebar” area to the “Right Sidebar” area (I’m talking in the Appearance -> Widgets screen).
Because my site is RTL, I need the sidebar on the left. I can drag all the widgets from right to left and all is good, until the next time it happens.
wow thats an odd one. I might need to take sone advice on this one, in the meantime have you tried the usual debugging techniques ie. Disable plugins, remove caches etc.