I noticed the same issue. This is easy to replicate as you can just put it together in a bot match.
If you have Guardian Project in play and cast a face-down creature, if you control no other face-down creatures you will draw a card, but if you do control another face-down creature it will not proc and you will not draw a card.
I believe this issue might come from MTG Arena misinterpreting rule 201.2c. The rule states that a creature with no name does not have a different name than another creature with no name, but in this case, Guardian Project is asking a different question. Guardian Project says "If it doesn't have the same name", which is different.
I checked with a judge and they believe that MTG Arena is wrong in this instance.
I noticed the same issue. This is easy to replicate as you can just put it together in a bot match.
If you have Guardian Project in play and cast a face-down creature, if you control no other face-down creatures you will draw a card, but if you do control another face-down creature it will not proc and you will not draw a card.
I believe this issue might come from MTG Arena misinterpreting rule 201.2c. The rule states that a creature with no name does not have a different name than another creature with no name, but in this case, Guardian Project is asking a different question. Guardian Project says "If it doesn't have the same name", which is different.
I checked with a judge and they believe that MTG Arena is wrong in this instance.