I am running pureos 8 beta, but I've run into this issue using pureos 7.

I receive a notification that software updates are available. I click on the notification, I then click Update All, nothing happens. I click the Update button, on the OS Updates widget, nothing happens. I close the application, run apt update and then re-open the Software application. I repeat all of the previous steps, with the same results. From my terminal, I run sudo apt upgrade. But each time I run into this problem, update-initramfs either fails or complains.

It seems like the Software application needs to provide some sort of feedback, indicating why nothing is happening.