I am 100% sure I came online every single day from the first onward. But after creating a ticket, staff says I didn't come online on the 13th. I know I did because that was the weekend our computers at work were down so I used my phone. I'm guessing that somehow it didn't count because of me using my phone instead of a computer somehow. Staff says there's no way they can prove it so they can't give me my day back. Now I'm sitting here feeling crushed, like literally crushed, like there's a heavy weight laying on me. This sucks. I was so excited to get another Nostalgic pet because there are so many I really like. Now I probably won't get it. This really, really sucks.
I just want to warn you all though, so this doesn't happen to you, make sure you don't use a mobile device to collect your Melody things. I don't know for sure if that's what screwed me over, but I'm pretty sure it is. sigh
Find out what items it gave out that day and account search them. Can't the staff find out where the items came from if they are on your account?
Either way, you can get a nostalgic pet still. You just need to log in 25 of the 31 days in september and collect to get it :)
Tell them to check the IP addresses associated with your account. They can apparently check that anyways. So if the phone's matches and the login matches...

I think the person I was talking to knows what she was doing. She's someone whose been here a while. I'll tell her though. But at this point I think she's probably done that already. I have more than a few IP addresses...one from home, one from my phone, one from work.
If it was consecutive days her count would be at 6. The achievement just says visit melody's cottage 25 times. Nothing about the first 25 or consecutively
And she should be able to check the location to each, regardless, and see which is the most logged in (I'm assuming from either your home or work.)
It's worth a shot.

But it's always worked that way. I don't know how it works now but previously the achievement kept counting because of the way it was programmed. The Essence of Melody wasn't supposed to go out if you didn't go all of the first 25 days, but it did (hence the thread I linked and multiple other threads about it from last year)
Well she said they would make it separate achievements this year and it isn't, so unless something does change, you are able to get an essence of melody thing if you miss a day. I'm not sure if this is intentionally changed or just another mistake on their part.
It happened before that it reduced by one number and I had to file a ticket but somehow it was fixed by itself..
Right, but she also said that getting the essence while missing a day was a mistake and you should file a ticket
What about your Shop Log for the record of the December 13th items?

I found a topic about the bug that happened at the 8th, maybe it effected you: (even Keith replied) https://subeta.net/forums.php/read/845638/Melody-Regular-2015-count-stuck
this is what happened to me on the 8th, but then it got fixed by itself, but maybe for some users it didn't.. so maybe yours was stuck on the 8th and you didn't notice and from now on it was counting one less day..
I don't think it is fair to expect users to know it's not working as intended without a clearer achievement description and if the problem happened last year and will again this year. I am sure many people will miss a day and get an essence and won't file a ticket. At this point, if they want it to be consecutive, they need to plan it better for next year instead of making the same mistake every year.
It's confusing, but I also think it has to be the first 25 days and consecutive. Literally every year I miss one day and although I've visited Melody nearly every day but one or two of them for the month of December, I haven't gotten the Essence of Melody. I got it last year even though I missed a day and created a forum asking if it was a bug or if I got it legit, and turned out it was a bug and I had to delete the item. I definitely think they need to make the achievement more clear. I imagine it'll be a problem again this year. I didn't know they were planning on making separate achievements this year but didn't implement it, however.
I think it was already suggested, but I'd check your shop log as well. It wouldn't hurt at least. If you don't see them on your shop log, then perhaps the page didn't load correctly or something that day you visited Melody? Since I'm trying SO HARD to remember to visit Melody every day to get that dang achievement this year, I'm literally double-, even triple-checking Melody to make sure the button says to Donate instead to visit.
To me, it feels like if they don't make the description clear and want it to work a certain way but it isn't clear at all, then change it later after a bunch of people get the achievement, it is changing the rules midway through the game. I don't care if previous years worked one way or another, not everyone remembers exactly how everything was in years past. This is why it bothers me.