Server Side Extension - "Error - The operation was cancelled"

[nsm1234567]

Hi there,

I've been experimenting with Server Side Extensions using Qlik Py Tools:  https://github.com/nabeel-oz/qlik-py-tools

Overall it seems to be working quite well.  My setup:

1)  I have Qliksense Enterprise (November 2020) running on-prem on Server1

2)  I have PyTools running on-prem on Server2

I'm running into a strange issue though when using the SSE calcs.  If I select something from a filter and then wait for the chart to finish calculating, there aren't any issues.  However, if I click e.g. the "green arrow" on the filter to confirm the selection before the object has finished calculating, the calculation immediately fails with a message of "Error - The operation was cancelled." 

Is this a known issue with SSE's?  I've tried searching for this error online and haven't found anything.  It's almost as though clicking outside of the filter box cancels the calculation somehow?