This is the 2nd report I've seen of this on iOS today. viewtopic.php?f=3&t=23767
was posted before you did. (And this is a client-side issue and has nothing to do with the map, so I think getting more folks into that thread in a similar situation would be sensible.)
FYI, you can tap-hold on the map to add a favorite or navigate as well. But you'd have to pan the map to find it first in this situation until we can figure it out.