There were some major glitches the whole past 48 hours and no one has even gotten close to trying to explain anything with something besides the normal rhetoric. It is most likely just a surge and clog issues, but you would think that mynxt would at least mention that things are fine. It is one of the few quick ways into NXT for the first time, otherwise we would go nowhere near that site.
As I mentioned above, MyNxt (as the third party service that it always has been, unrelated to the Nxt core dev team) lacked a developer for the last months after the previous dev left the community. And any time the service has required scaling or dependency upgrades, some of the features also needed code updates, or patching, or debugging. It really is not easy to find developers that have 1) The required skill set; 2) Are trustworthy enough to receive access to the site back end, even if all the MyNxt accounts are stored encrypted and only the users can unlock them; 3) Can commit to work the required hours and also stay involved for maintenance, never mind improvements.
And commitment is difficult to find when there's little budget. MyNxt has been basically breaking even with costs, little more. Recently the Nxt Foundation stepped up to provide support and some of the fixes have already been applied. Still, we're looking for a developer that can stay not just to fix bugs and keep the site in maintenance mode, but to add needed improvements. Also for the block explorer, that needs serious optimization work.
This weekend the two-factor authentication setup has been fixed and, to our knowledge the only issue pending in the wallet is adding new accounts to an existing wallet account. This should be also fixed soon.