1080P Night Vision IR no longer works

We have three 1080P cameras in our children’s bedrooms. In the last 6 months, the ‘night vision’ suddenly has stopped working for two of the cameras.

No settings had changed. It just stopped working. I’ve deleted the cameras and re-added them multiple times, but night vision still doesn’t work.

I’ve tried all the steps that I’ve read from other posts on here, but nothing is fixing the issue. Help!