On the latest snapshot (21.5.25) effects that cause you to look at or select a card in your library are currently not working. Memory Deluge and Thassa's Oracle both did not allow me to select a card. Memory Deluge brought up the library but allowed all 4 cards to be selected (but not confirmed) while Thassa's Oracle didn't bring up the library at all. Manually selecting the library also did not work.
#Effects that check library broken
ornate nexus
[[Memory deluge]]
deep nebulaBOT
Instant
Look at the top X cards of your library, where X is the amount of mana spent to cast this spell. Put two of them into your hand and the rest on the bottom of your library in a random order.
Flashback 
(You may cast this card from your graveyard for its flashback cost. Then exile it.)
austere kraken
Something similar is happening with hand disruption effects too.
Flipped a Revealing Eye, revealed hand but can't choose either card.
brave pelican
@austere kraken
Check if it's this problem
#1374910905703202839 message
You can test it with disable Card Images