I'm having this problem too, tried Tivo support and they were no help.
Uninstalled/reinstalled the Apple app, rebooted the Stream box, rebooted the Tivo.
Also won't let me login using my MAK, states it's invalid and must use my Tivo.com login and password.
If this keeps up I might be moving into the the "Stream is Crap" crowd! All of this worked last month, I don't use my ipod touch very often and it's nice to know that this is SO solid.
TiVo Roamio Pro
TiVo Roamio Plus (3tb)
TiVo Mini (three)