You didn't make enough space for the gifts. Hopefully, a regular house party is what you were after, because that's what you got!
And no matter how I try to delete everything, move the furnitures into the inventory or empty a room with a lot of space for the gift pile, it doesn't work.
Have the same problem? I have the solution for you.
If you had installed Seasons recently, or your sims were already staying in that house BEFORE you installed Seasons, you should just move your sims out to a new house.
So, maybe some of you are thinking, I really love the house/I spent a lot of time building it just for this sim family and I really don't want to move out.. I feel you, I really do.. Try the following solutions:
1. Download/reinstall the house you downloaded (from wherever you downloaded it from). If you already have the house in your Lots Library, you can skip this step.
2. Move your family out into the family bin or if you don't want it in the family bin, just move them out to an empty lot or a temporary house.
3. Replace the house with the 'new' one (the one in the Library that you just installed/saved when you built the house).
4. Move your family back in.
Q: I built the house myself and didn't save a copy of it in the Library or I forgot where I downloaded it from!
This may not work for everyone. It only worked for some of my saved games :(
1. Move the family out into the family bin or to an empty lot/temporary house.
2. Save the house in your Lots Library.
3. Bulldoze the original lot.
4. Place the house back on the lot.
5. Move your family back in
Q: It still doesn't work!
Download this mod made by NonaSims that allows you to buy the gift pile from buy mode. If you don't like installing mods in your game, you could have the gift giving party at another location. For me, I bought an additional house for my sim and they were able to have the gift giving party there.
Please note that I did not create this mod, and am not responsible for whatever it does to your game. This worked for me, and hopefully it will work for you too.