I was doing updates on the Ninja tab and realized it says I have zero fragments of this season's ninja (Kitsuchi) even though i've been completing each months' missions. I looked in my mailbox and it seems all of the seasonal ninja fragments are going there and will not let me extract them and keeps giving me a 'your bag is full' error (though any other ninja fragment from other events are collectable no problem).
There are also only about 40 fragments in my inbox which seems low for being three months in with a correct mystery guess, and the earliest one being from April 27th fairly late in the season, so I'm worried many of them may have expired as I was unaware they were ever there unable to be collected as they've never done that before...

Edit: a second account is working just fine and has 134 collected fragments, so this is specifically an issue with my main

What 'bag' would ninja fragments apply to and why is it even possible to be 'full'?