Thread:MasterTeska/@comment-45123716-20200420025917/@comment-4826222-20200420121806

This might explain it:

Why did I miss a day on the "contributing to the wiki every day" achievement?
 * The tracking for this achievement is based off server time, which is in the UTC timezone. For example, if you make an edit at 2 pm in the PST timezone (UTC-8) one day then another at 6 pm the next day, in UTC this will be counted as 10 pm on day one and 2 am on day three. We recommend keeping an eye on time in UTC if you are dedicated towards this achievement.

Found it here.