Hi triam31,
Upon checking the link that you shared, it says the upgrade of SDK should be to 6.5.x as per the release notes to match the PR.
The OS version that you are running 18.4R3.3 does not match this SDK version. It is 6.3.x on 18.4R3.3. Since this is internal data, much cannot be revealed about this.
I hope this solves your query.
Please mark "Accepted Solution" if this helps you. Kudos are always appreciated.