Data lookup definition not working onchange

[Kiranmai_KVL]

There is a requirement to set a field based on data definition lookup (similar to priority) but as below 

Based on A & B , derive C.

Based on X & Y, derive Z.

And based on C & Z, set the final value in field K.

We created on lookup rules for all the combinations. However  when changing the values of A& B / X & Y, values C & Z is not deriving as expected.. This is affecting the final value in field K. However this issue is intermittent.   

[Deepak Kumar1]

try running this code in global scope in the background script - 

gs.invalidateCache();

And check the form changes again.. This will fix the issue