Thanks for posting.
Right click on the backup definition in Reflect and select 'Edit'. Make sure that the correct partitions are selected and click 'Finish'
Conventional deletion processes don't appear to work since the XML file only exists somewhere in Macrium's internal programming.
The xml file is a regular file on your file system and is saved to the folder chosen when creating the backup definition. The default folder is: 'c:\users\<USER NAME>\documents\reflect'