Through Edits not deleting properly

I am having an issue with making through edits with the blade tool in the Premiere CC17 timeline. Some clips will display the white triangles indicating a through edit while other clips on the timeline only display a black line after the clip has been split.The issue is that when trying to remove the through edits by cmd+selecting them and pressing delete, only the edits with the white triangles can be deleted, while the cuts without triangles appear to be permanent and are unable to be deleted. Why would certain clips allow for through edits and other clips not? This is occurring in all of my Premiere Projects.

In the above example, with the blade tool I shift+cut vertically across 3 different stacks of clips. Some performed proper through edits, while others permanently split.

I am running Premiere CC 2017.1.2 on OSX Sierra