Though I was able to download the latest ConTeXt beta without any problems, my attempt to update my ConText-LMTX installation was blocked. The error message was

“mtxrun” cannot be opened because the developer cannot be verified

macOS cannot verify that this app is free from malware.

Safari downloaded this file on April 29, 2019.

I am not sure why this is happening and wonder if it would OK to copy mxtrun from my ConTeXt installation and replace the version in my ConTeXt-LMTX installation with it.

Alan