I am experiencing the very same or at least similar issue. I had the waitlist open for weeks in my browser, closed everything today and re-opened the forum again. After signing in I tried to access the waitlist. In one browser I get after some rather unusual loading delay a 500 internal server error. When using a different browser I am successfully redirected to HTTP 302 to https://login.eveonline.com/oauth/authorize followed by a 200 https://login.eveonline.com/account/logon?ReturnUrl=[...] but after signing in with eveonline, when returnign to the WTM waitlist I get the very same 500 Internal Server Error, which makes me wondering if it is on CCP's or WTM'S side.