Dutch and French authorities have cracked another encrypted communication service that criminals allegedly used to communicate with each other. The service, named Matrix, was the successor to previously cracked services such as ANOM, Sky ECC, and EncroChat. Police were able to intercept over 2.3 million messages and were able to read along with conversations for months.
Probably an implementation issue. Make a small error there, like storing parts of a key in memory or something like that and you’ve compromised security.