Dist Variance Hold due to tax lines not formed in Dist tables even after Invoice Validation process

Hi Team,

We are facing issue Distribution variance issue even there are valid distributions.

Issue Desc:

1) Invoice going Dist Variance hold after Invoice validation program completed /Warning. when i check those Invoice Distributions from front end i can see all Item line with save mode and Tax lines with preview mode.  if we run invoice Manually by going action--> validate ; invoice will be validated and also can validate by specifying  particular parameter ie by  vendor / invoice date/ Invoice number  but it is double work for us.

We usually schedule invoice validation program for all OUs (we have around 25 OUs)

here question is why Invoice validation program not working as expected. i suspect some tax calculation packages functioning while validation is under process.