I think I figured it out. The original had errors when saving and I noticed it had 'unlimited' listed for Production Run. When I removed that entry it saved OK and also appeared in the search. Adding 'unlimited' back again created the error on save. Thus, we actually have a bug with allowing non-integers into that field and/or how it handles it if that does happen.
The search is pretty poor though as it's always inclusive and you can't do multiple search terms as it will assume OR. Likewise you can't search on a specific field, searching for a deck that has say 2015 in the title will bring up all decks that were created that year. So yeah, it's a poor minimal function search, but not really broken. In this case the deck was 'corrupt' due to above bug and now working OK.
I marked the new deck as duplicate and will be deleted in the near future. Thanks for posting!
I did talk to Alex about this and he made a note of it for a possible future update in coming months. He's quite busy these days, especially with the upcoming decks and the 52+J. I also created an official bug report for this one that he and the developer will be using to evaluate and understand the current issues - https://unitedcardists.com/viewtopic.php?f=60&t=10614