Can't gift RP with messages

I tried gifting someone RP the other day since there's the sales of an additional bonus RP going on. Unfortunately, if I include a message in the text box and hit "Gift RP", nothing happens. If I clear the text box and click on "Gift RP", the window pops up with all the amounts of RP you can buy.

For a bit of clarity, the process usually goes like this:

1. Click on the "Click to browse the store" button on the League of Legends client.
2. Once the store is displayed, pick "Gifting Center" along the left hand side.
3. A new window pops up to select the recipient of the gift.
4. The different types of gift will pop up, click on "Purchase RP for a friend" box.
5. Enter message with the present.
6. Click on "Gift RP". A window pops up with set amounts of RP for you to choose.
7. Proceed with payment options.

That's how it should go from my own experience in the store. However, I can't get past step 5 if there's some sort of message in the box. I tried with one or all 140 characters and click on "Gift RP", but the window doesn't pop up. If I leave the text box empty, it's fine and the window pops up.

It could be just me that's facing this problem, so if anyone can try it out as well, it'd be helpful. I understand it's not a big issue, but it's nice to add little messages to your friends and special texts to your significant other.

Thanks for reading, have a good one!