Billing Address NOT being requested at checkout (& causing transitions to fail)

I'm hoping someone out there can help shed some light on this BUT even though billing address is required at checkout, some of my customers are not being requested to submit it and other are. The bigger issue is that now some customers are unable to complete purchase for payment plans because their bank is declining the transaction due to a billing info issue. 

I was sure I had billing address as a required checkout space, I even created a custom checkout field for it but the issue is still occurring. Very tempted to move to thrivekart at this point because this is a nightmare that is losing my business money!