My Mac is on MacOS High Sierra 10.13 (Supplemental) and my iPhone SE is on IOS 11.0.3. However my 4th generation iPad is unable to update to IOS 11 and therefore still operates on IOS 10.3.3.
Copy and Paste still works as it is supposed to between any device on the latest software, i.e. I can copy and paste from 1Password on my Mac into an App on my phone, or vice versa. I can also copy and paste into Notes on either device from either device from 1Password too.
However, copy and paste from the Mac or iPhone into the iPad does not work. No option to paste appears, either in Apps or in Notes.
So, it would appear that the ability to Copy and Paste from the latest and greatest software into an older version has been lost. I suspect that this is an Apple issue and not anything to do with 1Password. Please regard this as a heads up for anyone else with the issue, unless you folks know differently.
Again, just for info, here are some other issues I've noticed and reported to Apple, I know this is off topic for a 1Password forum, but just want to help:
1Password Version: Not Provided
Extension Version: Not Provided
OS Version: Not Provided
Sync Type: Not Provided