I just tried again and Opera did as you said - when I reloaded, it went to the fragment ID in the URL. I don't know why I didn't notice it before - perhaps because it's a recent change and I don't often refresh a page I'm in the middle of reading. I would consider it to be a bug - perhaps you would like to report it to Opera Software? I can confirm the same behavior on the Windows version (10.51).
Anyway, here's a workaround: when I'm about to change zoom, which sometimes makes me lose my place, I select some text (preferably a few words from within a single paragraph) and copy it to the clipboard. Then after changing zoom (or in your case reloading), I search for the text I just copied (Ctrl+F).