An error occurred during Tax Calculation .... Tax will be recalculated when document is submitted

We have just upgraded from 11.5.10 to 12.1.3  When we opened the system to a small number of users - all functionality in E Bus TAx worked successfully.  We had no issues with capturing requisitions or purchase orders.

However, when we released the system to the whole of business three days later - no requisition or purchase order that is form based can be saved. They all give the error listed in the subject line.  only iproc users can capture sucessfully.

I have followed every single metal link note found on this error and none of these fixes pertain to us.  The fact that it worked and then did not work - with no change to configuration is what perplexes me.