How to overcome feature blindness

I work on a product called AwesomeAds, a marketing platform that specializes in kid industry where users can create an ad campaign and monitor the performance of their campaign (engagements, budget spents etc)

A year ago we decided to implement notifications that will help our users keep a better track of their ad campaigns. We made a mistake to add an event that happens repeatedly multiple times each day, the result was Feature blindness:

Once we noticed our mistake, we removed these events and kept a very few events, but the damage was done and even we told these users that we fixed the notifications they didn't bother to check their notifications. If users don't check their notifications, they won't be notified about crucial changes to the campaign(s) or bad performing campaign(s).

Right now they can individually monitor each campaign but this manual monitoring won't scale, also we experienced lots of mistakes due to human error because they weren't aware their campaign wasn't performing well.

We have new users that use the notifications daily while the old users keep ignoring them.

We thought to change the UI, using a different colour and icon for notifications, basically changing the cognitive load:

Any ideas to break this cycle? Is changing UI enough to change their habits?