expression, noun, noun which may take the genitive case particle 'no'
things not going as hoped; unexpected mismatch; crossbill's beak (literal)
Idiomatic expression likening a situation to a crossbill's beak, whose upper and lower parts are misaligned. Often used in the pattern 〜の食い違い with the same meaning. The literal sense refers to the actual beak of a crossbill.
See also: イスカ
The plan ended up not coming together as expected.
Their opinions are completely at odds, like a crossbill's mismatched beak.
食い違い means a discrepancy or conflict in general, while いすかの嘴 is a vivid idiomatic expression specifically evoking the image of a crossbill's misaligned beak.
Standard kanji-kana mixed spelling; いすか is the bird name, 嘴 means beak.
Rare kanji spelling using 交喙 for the crossbill; 交喙 itself is uncommon.
Obscure kanji spelling; 鶍 is a rarely used character for crossbill.
From the observation that a crossbill's upper and lower beak parts are crossed and do not meet neatly, used figuratively for things that fail to align or match expectations.