I was using Liquibase 3.4.1 and wanted to use addAutoIncrement element. That didn’t work and after investigating I found the issue related to core library (https://liquibase.jira.com/browse/CORE-2521). In the issue, itself is said that the bug is fixed with release 3.5.0. I first updated my core dependency to 3.5.3 (latest one) but the error was still there. After downgrading to 3.5.0. my auto increment was finally added to the database.
Therefore, I think that it is possible that fix for CORE-2521 did not end on master branch but it was maybe just committed to 3.5.0 release branch and never moved to master (just throwing ideas, have no idea how are you doing your branching ).
I didn’t have time to check 3.5.1 and 3.5.2 versions…sorry!
Hope that this info is useful.
P.S. Postgres version is 9.6