Every time I open Sourcetree, it will ask for the password to be used with the Github account configured in it, as if it had never been set up before.

When I check my Mac's Keychain, I cannot find any entry for Sourcetree's Github account password in there.

Note that this issue only applies to the Github account. The password for the Bitbucket account configured in Sourcetree gets properly saved to my Mac's Keychain.