I am trying to classify an RGB image in ArcGIS 10.7.
When I try to use the 'select segment' option to create a training set I am allowed to pick only certain segments to add to my training set. For example, if there are 3 segments next to each other that belong to 1 class I am sometimes only able to select 2 out of the 3 segments. I don't get an error message but I'm simply not allowed to add the 3rd segment to the class I want, for some reason. In the corner of the ArcGIS window I get the message 'Oversimplified training sample selected'.
I have been able to successfully classify the image before, so I dont think there's a problem with the image itself.
What could I be doing wrong that is preventing me from using certain segments (that really do belong to the class I'm trying to ID)?