iMessage not sending only to certain contacts?

THIS IS NOT A QUESTION, IT’S A TIP

I have seen quite a few questions regarding iMessage and why it won’t work on only one contact or only works for a few and not others. I struggled with this for quite a while and regardless of the help and advice online, I could not restore it for certain contacts using those methods. Instead I did the following steps (please also see pictures attached) and it worked!

Settings—> Messages—> Send & Receive. Make sure that your mobile number is ticked under the section that says “you can receive iMessages to and reply from”

I realised that my mobile number was not ticked, so only people who had my iCloud email could iMessage me and Vise Versa.

I hope this helps!