A bug discovered in Watch Dogs: Legion, where the Xbox Series X/S version of the game doesn't autosave, is apparently set for a fix with an update scheduled for early December. After becoming aware of the widespread bug, Ubisoft announced the fix's December release on Twitter.
We're sorry about the issues you're experiencing. The team is aware of this issue and are working on a fix for it, which we're aiming to have in a patch in early December.
— Watch Dogs: Legion (@watchdogsgame) November 20, 2020
Currently, the only workaround that exists for the bug is for players to remember to save their progress manually, and often. While many players are reporting the bug for the Xbox Series X/S version of the game, we haven't found an issue in playing the PC version.
For more information on Watch Dogs: Legion, check out our Should You Buy.