Is iOs 18 compatible with MacOs 12 and iPadOs 15?

Sync'ing your iPhone XR and your iPad Air 2 with your MBPro are independent events. Similarly, sync'ing them with iCloud. The fact that the iPhone & iPad have different versions of iOS does not affect their ability to sync with your MBPro or iCloud.

The new Passwords app in iOS 18 does not replace or override the normal iCloud settings in your iPhone. Passwords is an optional app that you can choose to use or not. I do not use the Passwords app and my iPhone's interaction with my iCloud account & Mac has not changed one bit.

If you are currently sync'ing Reminders & Notes between your iPhone and iPad via iCloud that should not be affected if/when you upgrade your iPhone XR to iOS 18.

iOS 18 works perfectly fine with macOS Monterey 12.7.6. Sync, backup & importing photos/videos work fine with that combination. It's not the cause of whatever problem you are having.

When you say "import" exactly what do you mean ... sync contacts, sync calendars, sync Music, import photos to your Mac ...?

And if you haven't done it yet, shut down all your devices & restart them. (Full shut down, power off.) After restarting all of them, see if the behavior changes.

I am using iOS 18.1.1 on my iPhone and sync with a 2019 Intel iMac running Monterey 12.7.6. Have not had any problems.

It would help to know the exact model MacBookPro & iPad that you have.

I've unfortunately upgraded to iOS18 on my iPhone and now I can't import from my phone to my mac mini (late 2014) running OS12.7.6.

Will iOS18 be made backward compatible with OS12.7.6. Or is there a way to return my phone to iOS 17?

I plug my phone into the mac mini, open the Photos app and it opens the iPhone photos in the app and "prepares to import". Only it never prepares, instead the iPhone appears and disappears in the sidebar and "preparing to import" flashes on and off the screen.

I have

iMac (Retina 5K, 27-inch, Late 2015) running 12.7.6

and

MacBook Air (M2, 2022) running 12.6

and

iphone 14 pro running 17.6.1

i just want iCloud files to sync, passwords to sync, copy and paste between them and phone, contacts notes etc… All this works great now.

If I upgrade to 18 will it all still work?

Good to know, thanks. I did a restart. But I'll try a full shut down.

My iPhone 16 Pro with iOS 18 works perfectly fine with my iMac running Monterey 12.7.6. (Actually my iPhone is now on 18.1.1 and I am soon going to update it to 18.3.)