Hmm. Okay, so let me expound a bit on the oddities I encountered and hopefully it might help you. I encountered a very odd issue on my MBP Early 2011 that I did not experience on my iMac 2013 upon updating to 10.13.1. Oddly, my iMac installed the update just fine, however, my MBP installed it, went through all the motions, said the installed was completed and showed new various 10.13.1 features present, but somehow did not complete installation and I still encountered the issues you’re describing. When I would go to “About This Mac,” no matter how many times I would installed 10.13.1, it would still have the prior version of “10.13” listed there as the version the MPB was on. After speaking with several tiers of Apple Support, they all escalated it and I had to schedule another call for an Apple engineer to help resolve it. It was totally baffling to them and myself. Before that next call, I did more research and decided to reinstall the entire OS clean (and BTW doing so did a clean install, but did not require me to reinstall all apps or re-download or lose any files, ie - from Dropbox, files in my desktop, etc), and it automatically updated to 10.13.1 in the process— which I didn’t necessarily expect. Did you try a fresh re-install of the OS? What year/kind of Mac are your running? Agaib, a very important (and peculiar) thing to note is that when it looked like I had installed 10.13.1 but it really hadn’t fully installed, I never thought to look at “About This Mac” to verify it read version 10.13.1 and not 10.13 because several of the features of 10.13.1 were present on my MBP— even though it still read 10.13— such as the feature “split screen view when in full screen mode” in the Mail app. Meaning, when Apple shared my screen, they saw these features present so we’re very confused by the “mail sync, etc” issues still being present. But I was good after a fresh install. Hope this helps or at least reduces some things that could contribute to issues you’re encountering.