I have the same problem. I have tried a factory reset (both within the app and via the hardware button) but still get the error "Operation failed. Please try again later" whenever I try to change the notification settings. Notifications from the app are allowed in my android OS (but clearly this was never the issue anyway, given the error in the Kasa app). Notifications are set to "always" in Kasa, no matter what I try to set it to, as any changes I try to make give the error.

Screenshot of the error below - this pops up every time I hit 'back' from within the Notifications settings, even if I make no changes to those settings. It also gets stuck loading on this screen and I have to kill the app.

I have also emailed support and per their suggestions have tried on another device, and made sure not to be using a vpn or battery saving. None of their suggestions so far have made any difference. 

Model number is KC100, hardware version 2.0, firmware 2.2.28 which should be up to date. Kasa app is also the latest version (last updated 25 July), running on a Pixel 2 with the latest android 9 version. I will also send a message with the other info you asked for.

@Kevin_Z 

i have been reading this feed on getting notifications. None of these things have worked for my new spot pan tilt camera. Impossible to activate notifications ! 
thank you for any help you can give me 

k

@Katthor 

Hi, please refer to the instruction below to check the notification settings on the phone and APP.

https://www.tp-link.com/support/faq/2741/

https://www.tp-link.com/support/faq/1966/

What's the model number of your camera? Is there any error message when you activate the notification? Have you tried to reset the camera and test it with another phone?

Good day.