It seems that something broke in Splatoon after the last update. Some players have discovered a weird glitch that makes them invisible to enemy players.
A video was posted on Twitter (seen below) that shows how it works — it looks like it’s quite random, but once it happens, players run around the map invisible. Although it appears that player’s weapons sometimes pops up.
Nintendo hasn’t officially confirmed the existence of the glitch, but seeing as how videos are popping up on social media now, they probably are aware of it.
Splatoon will be down for maintenance on Monday, July 11, between 5 and 7 p.m. PT. Since the glitch was discovered so recently, there might not be enough time for Nintendo to fix it by Monday.
UPDATE: Nintendo has issued a patch that fixes the glitch. Splatoon patch 2.10.0 (9MB in size) can be downloaded now.
— 銅モデのぶんぶん (@squidcrouton) July 6, 2016