Hi all, enjoying all of my newly purchased CS aircraft, but there is an issue with overspeeding on the 767 that I don’t have on anything else. Here’s my workflow and the issue. Any insight would be greatly appreciated!

1. FDs on, AT Arm, VNAV, LNAV on. Runway course set to HDG, V2 speed set to IAS/MACH dial.
2. Press TO/GA power setting on the buttons above flaps indicator.
3. Press SPD button to engage AT on takeoff.
4. Gear up, Flaps up on schedule, Engage Autopilot. Change power setting above flaps indicator to CLB. Then when at cruise, change it to CRZ.

Speed under control during climb in steps approved by ATC - change alt as required, pressing VNAV engages climb between steps.

Once at cruise, it just goes into overspeed despite FMC showing .801 as the speed setting in MCDU. Engaging SPD button to correct and roll speed back to .80 - nothing. Still keeps overspeeding.

The only remedy is to engage speedbrakes. About 1/2 speed brake gets me to Mach .80 which is fine.

Am I doing something wrong? Is this a bug?