Hi Freelance, I just did the 10.13.1 update today and had a similar experience to yours....first time through, it did NOT install, but would no longer show as available on Software Update until a restart - then it became available as an update option, and this time it took. Thanks. So it's not just me. I did not have any problem at all with my 2017 MacBook Air and wondered if planned obsolescence was the issue.
iMac (19,1, 3.1 GHz i5, 12.7.4, 40 Gb RAM); MacBook Air (1.8 Ghz, 8 Gb RAM, 10.14.6, 256 Gb SSD) Vodafone router and Devolo Wi-Fi Extender, Canon TS8351 printer/scanner.
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