Request body not available when request is being made through corporate proxy HttpsProxyAgent

Minimal reproduction: https://gist.github.com/jaredxx1/e232f254d14e9589b3a400372209a801

I can't get the POST body when using an agent. Everything works fine if I disable the corporate proxy.

Result without agent option enabled: proxyReq: application/x-www-form-urlencoded 39 req data <Buffer 69 64 3d 63 66 63 38 66 36 34 62 2d 36 62 36 37 2d 34 62 38 61 2d 38 33 65 62 2d 30 37 33 35 61 35 32 31 66 36 33 66> req end id=cfc8f64b-6b67-4b8a-83eb-0735a521f63f

And result with agent enabled (new HttpsProxyAgent('http://user:pass@proxy-provider:30000'): proxyReq: application/x-www-form-urlencoded 39

I still get the correct content-type and content-length but the body is missing. I've also tried to listen on proxyReq 'data' events without success.

Any ideas?