You can check when you last got login coins (and how many times you've received login coins in total) by going to Settings --> Points --> Points log --> System rewards (bllue letters)
Perhaps its not been 24 hours since you last signed in? Go to your credits page and refresh. It worked for me. I didn't get my coins when I first signed in today either. So if it hasn't been sorted wait a little and try this. It may work too. Very good luck.
I checked it, and I see that I got 50 coins for login today, indeed what Strawberry Cat said is true. :)
I used the link and then you can see it, didn't know that, many thanks for the information. :)