[NTG-context] Losing a character during line break at a hyphen

Not sure whether this is a ligature problem or a hyphenation problem or both! In the following MWE, the line breaks at the hyphen following "Diffe", but one of the f's is lost so the PDF shows "Dife-". Latest LMTX, version 2021.08.19 19:48 \starttext Twenty years after receiving it as a Christmas present, I have finally got around to reading The Code Book by Simon Singh. Written in 1999, when E-commerce was still relatively new, the book provides accessible explanations of the workings of Diffe-Hellman-Merkle key exchange, and Rivest, Shamir and Adleman (RSA) public-key cryptography. \stoptext Output PDF attached. — Bruce Horrocks Hampshire, UK