It seems that Amazon's DTP support didn't know anything about the change (they asked the authors to provide ASIN's, so they could research the issue -- but this affected every DTP ASIN in the store). The employee assigned the "dtpadmin" login on the forum (if it's one employee, it's one with a fake registration date, from 1969, so is probably a shared login by an group of employees) later posted this note, at 1:41PM (presumably PDT):
Hello,Sounds a lot like the response following the recent uproar when all LGBT titles disappeared from the Amazon search engines and sales ranks. Hopefully this was just an "error," but as of midnight tonight (EDT), no corrections have been made to the actual book listings.
We have identified an error in our system. We are fixing the problem to remove the device limit for DTP titles. We apologize for this error.
Thanks!