After years of waiting, it is good that they seem to be moving on this feature, however the update today that supposedly added support for it is not working right.
The paycheck line item is there, and it under the "Category/Account" heading it shows [Account]/Roth401KContrib - so seemingly it should be categorizing it under a new "Roth401KContrib" category along with transferring it to the 401K accont. But it is categorizing it as _401Contrib, just like Traditional 401K, thus tax planner and reports are deducting it from income, which obviously should not happen for an after tax item. There is no Roth401KContrib category (tried adding it but it didn't change anything). I would also think it should be a hidden category with _ at the beginning but it is not under hidden ones either.
It is getting the _401Contrib category since it is added to the hidden "Tax Impact of 401(k) Accounts" account which tags all transfers with that category. After tax 401k contributions should not be put into this account.
@Quicken Jasmine please alert the developers to this - if people start using this while it is incorrectly set up they're going to have transactions that need to be fixed, or the next release will need to find and fix those transactions.