Using Version: 3.0.1.0 (1274136) 64-bit, selecting multiple words, right-clicking, and selecting Add Selection to Auto-Complete List does not seem to work.
Thanks for the report! This is indeed something on the list of known issues. For the moment you need to use the Project ▸ Project Settings... panel to add phrases directly.
Nice to know! I’ll try to look at the list of known issues before making a post next time.
No worries! I don’t think this one in particular has been reported on the forum before, or if it was it was a number of years ago in the beta area. The notes I had posted on it were from 2019, so it’s been around for a while.