Stage Fuel Not Correctly Reported With Engines Toggled With Activation Group

I have a craft with 3 boosters. In stage 1 I have only two of the 3 boosters activate. However, during the early stages of lift off I would like to fire the center booster as well using an activation group. However when I do this the stage fuel calculation changes to include the fuel tanks in the center booster and they continue to include these fuel tanks even after the activation group for the center booster engines has been switched back off. I can see the argument for the fuel calculations to include the tanks associated with these engines while they are active, but once they are deactivated I think the calculations should go back to only include the tanks connected to firing engines.

Repro

1. Create rocket with 3 fuel tanks side by side
2. Attach 1 engine per tank
3. Associate side egines with Stage 1
4. Associate center engine with Stage 2
5. Set activation group for center egine to 1
6. Launch craft, Full throttle, activate Stage 1
7. Enable Activation Group 1
8. Disable Activation Group 1

Expected

When Activation Group 1 is enabled the stage fuel remaining in both the flight view and in Vizzy should be the average of the 3 tanks.

When Activation Group 1 is disabled the stage fuel remaining in both the flight view and in Vizzy should only include the side tanks.

Actual

After Activation Group 1 is disabled the fuel is still the average of all three tanks.