Update (for me anyway): I called Citizens One this morning after reserving another iPhone. They were supposed to be able to tell after 24 hours the reasons why I got declined.
Unfortunately due to the volume of applications they received yesterday, they were backed up and did not have that information, and that department was closed because they don't have weekend hours.
She went through a lot of the glitches they did have yesterday to ensure that none of them apply to my account. The biggest being that Chase, Amex, and any "Business" card were for some reason declined yesterday. She also mentioned to ensure that my billing address on my credit card was the same as the one on the application that I did. (Mine was different, however she said as long as it's listed as a previous address on your credit report it should be fine.) But that this was a reason for a large amount of declines yesterday.
She did mention that there is a 3 attempt max before your SSN will be locked out of their system for 30 days. Fortunately for me, it only counts as a "new attempt" each time you use a new credit card for the application (according to her). So if you only tried one or two cards (even several times) she said you should be okay. She also mentioned to ensure with Equifax that there is no fraud protection, lifelock type stop on my account, because this could be the reason for the decline. I've never put anything on mine, but apparently a large number of people yesterday didn't even realize they had one.
She advised me to wait until Monday morning (more waiting, yay) when they would "for sure" be able to pull my account as to why. She didn't want me to risk going in again today to just blindly give it another go and then that be the reason I'm locked out for 30 days. She mentioned that if an account is locked out of their system, even due to glitch/error, there is no way to reverse the 30 day lock. Hopefully that doesn't hurt a lot of people on this forum.
So for now? I guess I wait until Monday.
We did go over every aspect that they look at when determining to the criteria for approval or not, and I passed every single area: Minimum Purchase was at least $400 max $4,000, number of missed/late payments reported (0), DTI (15%), not using a chase/amex/or business card, and ensuring it's a CREDIT card (preferably not linked to any bank account), and they don't have a minimum credit score requirement. As I said before, the only "negative"-ish thing on my credit history is I have a few hard pulls on my credit from buying a car back in February. She said however that those are low impact and not something they look at to approve/deny a loan.
Who knows. I'm very close to being over it at this point.