I have the same problem. FB17182730 filed with sample playground and diagnostics file.

I ran into this too, but managed to find a solution. The updateNSView method. was getting called very frequently and so reloading the table which lost the section. I made this function check if its data had changed before reloading and that worked. I had passed the data to the Coordinator for use in the data source & delegate, so this code worked for me:   func updateNSView(_ nsView: NSTableView, context: Context) {     if tableData != context.coordinator.tableData {       context.coordinator.tableData = tableData       nsView.reloadData()     }   } The elements in my data array were already Equatable, so this works fine.

Thank you. The tip to create a scheme with "Debug executable" turned off in the Run settings is working for me. No ideal but at least I can run my apps now.

I found that I could open the project in Xcode 12.0.1, add the package dependency and then go back to 12.2. Seems to work fine but hopefully 12.2 will be fixed soon.

I have the same on an Intel MacBook so it isn't just a DTK issue. Big Sur beta 8, Xcode 12.2 Filing a feedback.