Process builder email alert does not trigger with a bulk update, only with a manual update

We have a Process Builder email that WILL trigger when you make a manual update to an Account but when using a tool (DemandTools) to do the same update the email does not send (we're talking about only 70 records). Any ideas on what is preventing the email from going out?    The email is to alert the billing contact on an Account when the Invoicing Status is made 'Terminated' and the Inv Status Reason is made 'Non Payment'. As a test this morning I did that change MANUALLY on 1 test account and I got the email no problem. When I tried the same exact update to that single account with DemandTools I got no email.     What might we be missing?      Thanks,    Mike