@sgunhouse Again, thank you!!! But with GREAT respect I think you keep missing the point.
A) I of course have it set to reopen all tabs upon reopening Opera - so I have it set to a Session if that's the proper term - thank you!
B ) Had I REMEMBERED there were TWO open windows - which I NEVER have - I would have shut the second before rebooting. I forgot there were TWO WINDOWS open, and the problem is that WHEN THERE ARE --TWO OPERA WINDOWS-- OPEN IT WILL LOSE THE TABS OPEN IN THE FIRST WINDOW AND ONLY REOPEN WHAT WAS IN THE SECOND WINDOW.
C) Why I didn't initially panic was that the last time this happened - several iterations of Opera ago - I was able to go into History and if I dove deep enough, the PREVIOUS time that I rebooted when it had properly reopened Opera - I would see that list of tabs clustered together as they would have "reopened/reinitialized" themselves the LAST TIME OPERA OPENED WHEN IT --DID-- OPEN ALL THE TABS.
What made this instance so horrific is that while I HAD reopened and closed Opera - and thus reloaded all my tabs - in recent memory, when I went into History as far back as a MONTH there was NO instance of the tabs reopening in a clump so I could find them!
So it appears the problem is that somehow now in Opera when it reopens all the tabs upon rebooting it DOES NOT write them into HISTORY. This is truly bizarre and I don't get it. Now mind: I did NOT "touch" the tab and watch it individually reload, but that last time before the problem when Opera reloaded each tab circled and then the name of the site showed up on the tab as if it HAD reloaded the tabs which SHOULD have "written them" into Opera's History.
So I guess the BIG question is: is this NOT true? Does one now have to click on EACH INDIVIDUAL tab and make SURE it "fully reloads" to ensure it appears in history?