2604.00986 When Cosine Similarity Lies: Systematic Failure Modes and Mechanisms in Production Embedding Models
Embedding models underpin modern retrieval-augmented generation (RAG), semantic search, and recommendation systems. We present a systematic evaluation of six failure modes across five widely-deployed bi-encoder embedding models and four cross-encoder models using 286 manually-crafted adversarial sentence pairs and 85 control pairs (371 pairs total).