Why does the node inspector not start when I am using nodemon and ts-node?

With ts-node 5.0.0 you no longer pass the --inspect flag the same way. The suggested way is node --inspect -r ts-node/register path/to/ts. For example:

nodemon --watch src/**/* -e ts,json --exec node --inspect-brk -r ts-node/register src/app.ts

see https://github.com/TypeStrong/ts-node/issues/537