Payment Terms Changing Upon Invoicing

Payment Terms Changing Upon Invoicing

Hello!
Our standard payment terms for 95% of our customers are Net 30, and all of our customers that these terms apply to have that setting n their customer profile. 

However, over the last week or so, when an invoice is generated the majority of these Net 30 customers are getting On Receipt as their terms. We haven't changed anything else on our side. Has anyone else seen this happen?