Are egg matzos treated as bread for purposes of an Eiruv Chatzeros?
The Aruch Hashulchan in Siman 367 #15 writes that there is room to query whether the bread must be the kind over which Hamotzi is said or if any "bread" on which Mezonos is said is acceptable. He quotes Rabeinu Yerucham as cited by the Darchei Moshe in this Siman who writes that the Eiruv can be made with "Lachmaniyos." In Siman 168 #8, two kinds of Lachmaniyos are described; those which are made from a thick dough are considered to be Hamotzi while those made from a batter are Mezonos. The Aruch Hashulchan's assumption is that the Lachmaniyos Rabeinu Yerucham refered to are those on which Mezonos is said, and they may be used for an Eruv.
Egg Matzos are Mezonos and so would fall into the query of the Aruch haShulchan.