I face this problem too. Github told me
" Dec 9, 10:58 PM UTC
Hi Fanon,
Taking a look at your contributions from 2018 I see that you made quite a lot of contributions during November and December of 2018. As the year 2019 progresses, some of those older contributions made during late 2018 are falling off and are no longer included in the contribution count for the past 12 months. If you visit the link for your contributions during 2018 you will still be able to see these 350 contributions. "
I face this problem too. Github told me
" Dec 9, 10:58 PM UTC
Hi Fanon,
Taking a look at your contributions from 2018 I see that you made quite a lot of contributions during November and December of 2018. As the year 2019 progresses, some of those older contributions made during late 2018 are falling off and are no longer included in the contribution count for the past 12 months. If you visit the link for your contributions during 2018 you will still be able to see these 350 contributions. "
That's interesting, I'll have to check that out.