syncing iPhone (ios14) with High Sierra using itunes

I received message to update my iPhone Xs to IOS14.0. I connected to iTunes on iMac with High Sierra to do make a backup to the computer first while doing the download only. After download was completed, I selected update but nothing happened. I disconnected and reconnected, saw the update button, but nothing happened when clicked. I disconnected and decided to do the update and install from the iPhone directly. Upon completion, I reconnected to iTunes, heard the usually beep, but NEVER saw the iPhone icon in the left corner. So now there is not way to do any backup or update to computer nor can I get to the recent backup on computer to restore (I can use yesterdays backup to iCloud on phone if needed, but not as ideal as more recent computer backup). I have restarted iMac and restarted iPhone but nothing. Of course this computer version will not use the Finder for syncing so what to do now before restoring from iCloud phone backup as last resort.?