LED FLASH FOR MESSAGES

I used to have this feature turned on on past iPhones and it was great. When my phone was on silent or regular sound if the screen was off I would get flash notifications for everything including text messages. I have an iPhone X’s Max and the flashing light will not work with messages. I’ve tried everything I know how to do or change and even engaged Apple support (worthless) trying to get this feature to work with messages again....... it works with every other notification!

Any suggestions ? Help? 

Thanks in advance!