Problem with Expression Controls Not Updating

I’ve been encountering a persistent issue with Expression Controls in After Effects, and I’m hoping someone here might have a solution or insight.

Here’s the problem:

I’ve set up Slider Control and Checkbox Control on a null layer to dynamically adjust some properties (scale and opacity) across multiple layers in my composition. While the expressions work fine initially, they don’t seem to update dynamically when I scrub the timeline or adjust the slider values. The only way I can see the changes take effect is by manually refreshing (purging cache or reloading the project).

This issue becomes a real bottleneck, especially when working on more complex compositions. I’ve tried

the following troubleshooting steps:

Resetting preferences.
Disabling and re-enabling hardware acceleration.
Testing on multiple versions of After Effects (2023 & 2024).
Purging cache regularly.

Still, no luck! 

While troubleshooting, I documented some of my findings on my website: https://dogumgunumesaji.org/. If anyone is interested, you can check it out for additional details.

Has anyone faced this issue before? Could it be related to my expression setup, or is this a performance limitation in After Effects? Any advice or workarounds would be much appreciated!

Thanks in advance for your help.