iTunes does not see iPhone, but only in 1 account

tt2: My issue - iTunes not recognizing iPhone - has been resolved. Given your efforts, and perhaps in future helping others with the same seemingly intractable problem, I came back to explain.

Short answer: User error.

Long answer follows:

It turns out that your initial feeling was close to the mark; you were wondering if, somehow, version numbers might not be lining up among all the different pieces. You were right, but there's a piece to the story I did not mention as I didn't think it would be important. I have been in the position, many times, to help people trying to solve computer problems; that is why my initial question contained much information about my system. But I missed something.

Just like those police procedurals on TV where the detective wants everything that can be remembered, no matter how seemingly trivial, that's what we have here.

My iPhone is in the Apple iOS beta program. For some weeks the phone has asked me to update. I was ignoring it, partly because the 'red circle' indicating that an update was needed was appearing, not on the App Store icon, but on Settings. These updates tend to be lengthy always involved a re-start, with takes the phone out of service (for 20 minutes!!)

I ran the update. Plugged the phone into MBP, which immediately recognized the iPhone. The system is now working as expected.

Thank you again for thinking this through. Had I given all of the information likely you would have solved it. I'm marking this question "Solved" because I think it can help others.

Did everything. The apparently faceless app starts, according to Activity Monitor, but sadly, no suggestion to upgrade; nor do I see where such a suggestion could appear? Restarted, too, just to beside. Did I miss something?

I might have mentioned in my initial post that Calendar is not synching with the computer, either; changes made on either end fail to show on the other. Syncing with the third-party application "Things" works perfectly; this app uses its own system, though.

Argh. iTunes is still recognizing the iPhone in my Test account, but no changes in my working account. I did reset the dialog warnings, as you asked, in both accounts, and haven't seen any formerly suppressed dialogs yet (and not clear on what you are after on Reset Dialog Warnings - perhaps it's another mechanism that seek permission for an update?). Of course I quit iTunes each time, and then fired it up again. I haven't restarted the computer.

In any case no change. And to me the fact that the devices is not recognized only in one account somehow holds the definitive clue, but darn if I can see it.

"Seems a bit defeatist" - I am laughing so hard that I - no, wait a minute! Wait! No, I'm crying, not laughing!

Actually, I thought about doing exactly that; but if you are like me your workspace is very heavily customized, all sorts of gadgets running; changing would also involve new login credentials and all sorts of things.

But more importantly such a 'solution' is just plain ugly. Very dissatisfying, especially as there's a way forward in there.

If I can figure out a way to reinstall the iPhone software, that's my next step, and thanks.