I am following the on-line tutorial "Using the Segger J-Link Debugger with the MKR Boards". I am using an Adafruit M0 board with SAMD21G18 chip. I have wired the SWD interface as instructed and have created the "debug_custom.json" file. However, when I connect the board and the J-Link to the PC the Debug Icon in the menu bar remains greyed out. When I hover over the icon I get the message "Debug - No programmer selected for 'Adafruit Feather M0 (SAMD21)'". I think that the J-Link is properly connected to the board because when I run the Segger J-Link GDB server app it indicates that it is connected to the target.
I moved your topic to an appropriate forum category @robertparker1764.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.