I have had the same problem as the person who first launched this message. Here is what I discovered:
In the Settings/iTunes Wi-Fi Sync section I have 2 listings for my PC. The first one is the currently installed PC It only has Books and Photos listed
The other occurrence of my PC that is listed is the version that I previously synced with iTunes prior to re-installing Windows earlier this month. This PC version does not exist anymore!!!!
The message that I get when I tap the arrow is that Sync will continue when that version becomes available again (which is never going to happen).
The Apps and Music are listed for this version of my PC.
Tapping "Sync now" does nothing. I am trapped in a time warp unless I can uninstall that prior version of my PC and by the way, the names for both versions are identical which means if I can figure out how to get rid of the version that no longer exists, it will delete my current version as well.
OK, so how do I get rid of the earlier version from iTunes?
Thanks for ANY help
Bob