Consumers have submitted hundreds of complaints about the p2p payments app because they are unable to sign up or access money that was sent to them; the reason behind the issues is Zelle’s security structure is very similar to that of a bank; if something doesn’t match perfectly or the users bank is outside the Zelle network then its possible they will not be able to sign on; Zelle initially launched inside their bank network only, but in September they launched their stand alone app and thats when the issues began; the company is looking at improving the process but says they will not compromise their security. Source.
