Visual Builder - for Each running in parallel mode

Summary:

I have created a VB extension and have some custom logic based on forEach. I have some complex logic inside ForEach but even though I have set the mode as "Serial", I can see inside activities are running in parallel mode and are creating issues. How to force foreach to run in serial mode?

Note - I have checked the code, and I can see async, await in for each, and also mode set to serial.

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