I was finally able to gift again this morning and then later received this reply from GI:
Thank you for contacting Game Insight Support Team!
My name is Mary and I am glad to help you.
I have to inform you that in the last update the gifting system has undergone some minor changes. the maximum amount of gifts you can send a day equals 300. But form now on the counter works individually for every gift you have sent. I will illustraate it with an example. For instance, you have sent out 50 gifts at 7a.m. and then 250 gifts more at 9 a.m. According to the new rules the counter will now drop individually for these two groups of presents, thus, 7 a.m morning next day you will be able to send only 50 gifts, and the rest 250 will be available for gifting starting from 9 p.m
Should you come across additional questions you need my assistance with, please feel free to e-mail me back and open the request for a further discussion.
Your Game Insight Support Team