Everything was working fine with Arm DS 2021.0.
I have just installed Arm DS 2021.1.
DS 2021.1 will load the workspace / project and build without any problems, but I cannot start a debug session. The error reported is:
Script C:\Users\XXXXXXX\Development Studio Workspace\.metadata\.plugins\com.arm.debug.cmsis\DS-MDK\SAMA5_DFP_ATSAMA5D27\dtsl_config_script.py does not provide configuration DtslScript_DebugAndOnChipTrace.