It could be your bank and not the Disney site. Especially with all the breach stuff that has gone on. My bank has done this to me in the past.
Eighteen months ago, we started our WDW vacation with a two day stop at US, staying at RPH. I checked in with a credit card because hotels almost always put a hold on debits. We went to Publix and bought water and snacks, no problem with debit. Ate at Three Broomsticks, debit declined. DH freaks, I pay cash and try to convince him that it is just a glitch. It is a Sunday and we use a credit union, so no one to call, but I go online and show him that there is plenty in the account.
We stop at TCBY in citywalk, debit card goes through without a hitch. Check out of hotel next day with debit, again no problem, so I assume glitch was with Three Broomsticks. We move to WDW and charge back to the room until I try to use debit in World Showcase, declined. We go off property, declined at CVS. I call bank and am told that FL is on their watch list and they won't authorize charges without us telling them we are going. I raise Cain, am promised card will work from then on. Sometimes it did, sometimes it didn't. Several Epcot CMS told us they see it all the time, and that how the charge is run and by what type of company (restaurant, store, etc) makes a difference.