I uploaded two game save files I had the issue with (though you will have gotten one twice, since I couldn't remember which one I chose to upload first).
One starts the morning before the wedding took place and the other is a save while the wedding is going on and you can see that the 'take the first piece' task for the wedding is still outstanding.
I have not tried to have another wedding in any other save file; I don't usually have wedding events, I tend to have them elope.
I did attempt this wedding twice in two different locations; the first time I exited without saving (I had this wedding event at the park in San Myshuno, I made the cake and brought it and when that didn't work, I had a Sim make another cake at the venue and that didn't work either).
My second attempt at a wedding was held at their penthouse (in the same save file) is what is here. FYI, the cake was not made by either of the newlyweds but I did attempt to make another cake with one of the newlyweds and that didn't help. I did not save that, I just tried it and quit without saving.
I will try to see if I can replicate this in any other save files, but I only have one file where the couple is in a position to hold a wedding. They are also located in San Myshuno. I will let you know whether or not they have the same problem.
Thanks and regards,
Jennifer